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Topic: Fuel Pump Replacement and Dropping Fuel Tank (Read 1421 times) previous topic - next topic
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Fuel Pump Replacement and Dropping Fuel Tank
I'm looking for advice about what to do in this situation.

Last week my LD would crank but not start.  Suspecting a fuel pump, I talked to a local mechanic about it (including size/weight/etc..) and he said no problem bring it in.  I called coachnet and had it towed over.  He does a diagnosis which includes testing the fuel line for pressure and squirting starting fluid in the throttle body.  He says no fuel - it needs a fuel pump.  I agree to the repair. 

Today he calls and says it's too big and he can't do the work.  He tried to drop the tank and couldn't get it out from under the vehicle.  He decided to put everything back together and now it starts and runs.  His theory is that he put some pressurized seaform in the fuel lines while doing the diagnosis and maybe that cleared things up.  I'm skeptical.

Now I need to decide if I should (a) drive it home and hope for the best or (b) take it to another (more carefully chosen) shop and tell them I want a new fuel pump even though it runs fine and I'm not all that confident in the first diagnosis.

Ideas?

Rich
'03 MB in NC
2003 MB
 
Re: Fuel Pump Replacement Decision
Reply #1 –
A bit aggravating when they have the rig then decide they can't do the job. Probably for the mechanic too.

I would take the middle path- find a good garage that can do the work and have them analyze it from the start (no pun intended).

I had a fuel pump put on my 92 MB. The shop did it in their lot, with jacks and jack stands from underneath. Maybe the 03 is different. A good mechanic is a treasure.

For comic relief: https://m.youtube.com/watch?v=9qsnSLDEqMc the scene from the movie Head Office in which Rick Moranis is dealing with his Mercedes mechanic. It is a side splitter.
Paul
'92 Mid Bath
Re: Fuel Pump Replacement Decision
Reply #2 –
"He tried to drop the tank and couldn't get it out from under the vehicle."

Rich

I am now running on my 3rd fuel pump ('04 30'IB, 89000mi).

It is not necessary to take the tank "out from under" the vehicle.

The 1st replacement was done with the LD positioned over a pit inside a shop where I could not watch. The 2nd replacement was done outside, up on a lift, where I could watch. Here the workers had built a platform under the vehicle to support the tank while the work was being done. It will make the job much more easy if the tank is nearly empty.  ;D

While the tank is down make sure the technician replaces the short pig tail that connects the generator fuel line to the tank output. It will fail sooner or later. Ask me how I know that!!!! It was on still another occasion that mine was replaced and a stainless fuel line was installed all the way to the generator.   8)  
Steve S.
Lazy Bones & Cedar
2004 30'IB (Island Bed)
Yesterday is History, Tomorrow is a Mystery
Live for the day!
Re: Fuel Pump Replacement Decision
Reply #3 –
Rich,
First reset the rollover safety switch (mine is above the right kick panel by the heater). 
If the pump is 55,000 miles old, I would encourage the shop to put the rear tires up on 4x4 blocks to remove the tank and change the pump.
I think they are unsure as the failure starts out intermittently and and is only detectable at low fuel levels and maybe at starting. 

I have an '88 MB with the 470/7.5L V8, and Frame rail mounted injection pump with in tank transfer pump.  In this forum it was indicated the tank pump lives about 55.000 miles.  My in tank pump failed as I drove it home from purchase (57,000 miles), and it would run well until the fuel level reached the 3/8 mark.  Then it would not go faster than 40 mph.  It is a brushed motor and "brush wear out" gives intermittent failure until the armature slings solder or it looses contact with the commutator.  Jiggling bounces the brushes back into contact with the commutator and the pump will run for a while.
Rodney
1988 Mid Bath
Re: Fuel Pump Replacement Decision
Reply #4 –
If the mechanic did check the pump and found the pressure out of specification, then a new pump is in order.
Your rig is old, like ours, and the pump probably has a lot miles on it. Fuel pumps, of our LD's vintage, have a poor history of longevity.
Our 2003 has 98,000 miles and I wonder if the pump should be changed as preventative.
Would rather change it at home instead of finding someplace that can handle it, 1500 miles from here.

Aged fuel pumps can be intermittent, sometime a good wack on the bottom of the fuel tank is enough to free up...for a while.
Then again, your LD's could have be an intermittent electrical problem that cut the power to the pump.
Wonder if he checked for power at the fuel pump, before he dropped the tank?
A dirty plug, at the tank, could have been the problem. At this point, it's all a guess.

Your 2003 LD should have a drain, at the bottom of the fuel tank, that can be used to completely empty the tank, before dropping it. 
A small amount of remaining  fuel, even two three gallons, will make the tank more difficult to handle.
The power of sloshing is easy to underestimate, unless you are an experienced boater.
While the pump can be changed, partially dropped, it might be a better idea to pull the tank out for a good internal cleaning and inspection for rust.
As Steve suggested, replace the fuel line that goes from the tank to the generator.

Larry

Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze
Re: Fuel Pump Replacement Decision
Reply #5 –
"In this forum it was indicated the tank pump lives about 55.000 miles."
----
Don't tell my 100k+ fuel pump about this!  :o

Joan
2003 TK has a new home
Re: Fuel Pump Replacement Decision
Reply #6 –
Quote from: paul banbury  - 
A good mechanic is a treasure.

Indeed!  The mechanic I used to take the LD to closed his independent shop because of the hassle of running a business.  He now has a bay at a high performance off-road shop and just does transmission work. 

I left out part of the story in the interest of brevity.  Best I can tell, they managed to drop the tank despite it being 1/2 full of fuel.  They then wanted to slide it out from under the vehicle and it wouldn't quite fit.  This led them to try and lift the RV on a 9,000lb lift despite a previous conversation with me about the RV weighting closer to 13,000lbs and him pointing out that the lift was only rated to 9,000.  A cable in the lift snapped, and at that point I think they were just scared of what might happen next.  Following that story, relayed to me by phone, I decided that moving the RV to a different shop was was a pretty good idea. 

Quote from: Lazy Bones  - 
While the tank is down make sure the technician replaces the short pig tail that connects the generator fuel line to the tank output. It will fail sooner or later.  

Yes!  I had this on the list of things to do.  Given the story above I'm not sure if he would have followed through or not. 

Quote from: rodneyhelfrich  - 
If the pump is 55,000 miles old, I would encourage the shop to put the rear tires up on 4x4 blocks to remove the tank and change the pump.
I think they are unsure as the failure starts out intermittently and and is only detectable at low fuel levels and maybe at starting. 

I'm at 70k.  I have HWH jacks and offered that those and some jack stands could safely lift and support the rear of the vehicle but after the lift incident (see above), I think all they want to see is the RV driving away.  I'm afraid that  the problem is intermittent and I'll regret it later if I don't replace the pump now.  I had some extra cranking before starting on the last trip and in retrospect it was probably a warning sign.

Quote from: Larry Wade  - 
If the mechanic did check the pump and found the pressure out of specification, then a new pump is in order.

I thought he did, and as he told me last week that he used a fuel pressure gauge (0 reading) during diagnosis.  Today it sounded like he just disconnected a fuel line and looked for squirting fuel instead.  I personally checked the safety switch, fuse, and relay before bringing it to him so I know that part was done correctly. 

It is all a guess, and I'll be interested to see if it starts again in the morning!

Rich
'03 MB in NC



2003 MB
Re: Fuel Pump Replacement Decision
Reply #7 –
I chose a different approach and mounted a second fuel pump (Airtex) on the frame rail near the fuel filter with all necessary fittings and hoses. I can remove the fuel filter and replace it with the auxiliary fuel pump. It's power comes from the standard fuel pump control module. The wiring is there, just has to be connected. It does pump fuel with the tank pump off but I have not connected it up and driven it.

I can't recommend anyone else do it since it hasn't been completely tested. I did it because the RV is parked in the backyard between fence, house,and alley with no way for a tow truck to get in there and tow it out if it won't start. Stored with a full tank repairs would be difficult. I haven't put the connector on the power line yet because it would require cutting and putting a connector in the standard wiring. I decided to wait till I needed to cut the wiring before doing so.

I think I wrote it up and posted it a year or two ago. It has been too long to remember part numbers. The most difficult part was duplicating the fuel filter fittings in the lines from the fuel pump. Those fittings are called bundy tubes.

I don't think much interest was shown at the time but I rest easier thinking that no matter where I am when the fuel pump fails I should be moving again within an hour. If I would complete the wiring I could do it beside the road in ten minutes.

I also carry a replacement OEM fuel pump. It was expensive and took several days to get in Phoenix. Probably a few more days in a remote location.
Just an idea.
Harry 2006 RB
Harry 2006RB
Re: Fuel Pump Replacement Decision
Reply #8 –
Rich,
Oh man what a story.  Lucky those Mechanics did not kill them selves.

I reference to the O psi pressure from the in Tank "Transfer Pump. As far as the 1988 and 1991 Econoline Chassis I have, the in line fuel pressure is nearly Zero while in operation.  The "In Tank" pump pumps to the Reservoir Filter Cup in the left frame rail with a return to the tank.  The only significant back pressure is gravity, the Reservoir Filter, and the rubber flap check valve on the return tube inside the fuel tank.  People take the Strainer out of the Reservoir Filter Cup most of the time.  The frame mounted Injector pump draws fuel from the reservoir , pumps to the fuel rail and injectors at 50 PSI or so, with a pressure relief back to the Reservoir. 
Rodney
1988 Mid Bath
Re: Fuel Pump Replacement Decision
Reply #9 –
Where the fuel pump is being replaced, do the new pumps have the same inherent flaws?

Matt
Re: Fuel Pump Replacement Decision
Reply #10 –
"Where the fuel pump is being replaced, do the new pumps have the same inherent flaws"

Yep, OEM, made in Thailand I think. Maybe they have made improvements but we wouldn't know that. I was surprised to see how small the pump module is.
Harry 2006RB
Harry 2006RB
Re: Fuel Pump Replacement Decision
Reply #11 –
Quote from: hbn7hj  - 
"Where the fuel pump is being replaced, do the new pumps have the same inherent flaws"
Yep, OEM, made in Thailand I think. Maybe they have made improvements but we wouldn't know that. I was surprised to see how small the pump module is.

The pump itself is small, about the size of a can of tomato paste.
I usually recommend replacing the whole assembly unless an OEM pump assembly isn't available.In this case, I recommend a Bosch pump.

Larry
Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze
Re: Fuel Pump Replacement Decision
Reply #12 –
Quote from: hbn7hj  - 
I chose a different approach and mounted a second fuel pump (Airtex) on the frame rail near the fuel filter with all necessary fittings and hoses.
I don't think much interest was shown at the time but I rest easier thinking that no matter where I am when the fuel pump fails I should be moving again within an hour. If I would complete the wiring I could do it beside the road in ten minutes.
Just an idea.

I remember the thread well and had hoped you would report back on how it worked.
If you ever decide to test it at home, please report back on the results, it's an interesting idea.

Larry
Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze
Re: Fuel Pump Replacement Decision
Reply #13 –
The pump produces fuel pressure when hooked to twelve volts so I'm confident it will work. If I ever hook it up to the fuel pump module like the original is I'll post the results.
Harry 2006RB
Harry 2006RB
Re: Fuel Pump Replacement Decision
Reply #14 –
Follow-up on the original story:

I drove the RV to a better mechanic and he took it for a long drive with a fuel pressure meter attached to the fuel rail.  After more than an hour in all kinds of driving he saw nothing that indicated the pump wasn't up to specs.  After talking with him, I decided to take my chances and keep driving it.

I used it for every errand for the past 8 days or so and never had a single problem.  I understand that I might still have a problem if there is a bad spot in the fuel pump and I land on the unlucky spot again.  On the other hand, maybe it was an electrical problem (wiring harness, as suggested above?) which was resolved when the tank was dropped by the mechanic who backed out on the job. 

For now I'm carrying a jumper wire so I can remove the fuel pump relay and send power straight to the pump.  If I find myself with a crank-no start again, I can jumper the fuel pump and crawl under to listen for the pump sounds.  I'm also carrying a rubber mallet so I might be able to jar it to starting if I do have a problem.

In the mean time, I'm going to look for an opportunity to change the fuel pump myself.  I'm thinking about using oversized ratchet straps to drop the tank like this guy did :  https://youtu.be/s7kVEe77n7E?t=5m20s

One advantage of doing it on my own schedule is that it's far easier to empty the fuel tank while the pump still works using the relay jumper wire and the fuel filter disconnects. 

We'll see how it goes.....

Rich
'03 MB in NC
2003 MB
Re: Fuel Pump Replacement Decision
Reply #15 –
I'm sure this is in my future, too.  The 'threaded rod' method in the post below is probably how I'll do it (solo), as it keeps alignment under control, and probably can be done without a jack if you're patient.  (I have a small transmission jack, so no worries either way.)

Cost estimate to replace generator fuel line

Chip
2000 Front Lounge
Re: Fuel Pump Replacement Decision
Reply #16 –
Quote from: Chip Chester  - 
I'm sure this is in my future, too.  The 'threaded rod' method in the post below is probably how I'll do it (solo), as it keeps alignment under control, and probably can be done without a jack if you're patient.  (I have a small transmission jack, so no worries either way.)
Cost estimate to replace generator fuel line
I wrote the posting on how to lower the tank with threaded rod. My user name was mixed with Laramie RT, during the transition to the new forum site.
I have use threaded rod to lower the tank enough to replace the generator's fuel line.
With a long enough threaded rod, the tank could be lowered and set it on a furniture dolly and then rolled out.
Trying to change a pump, while it is still under the motorhome, is going be very difficult or impossible. You will need to raise the rear of the LD high enough to clear the tank, plus the height of the dolly.
 A low profile transmission jack would be my preference, over a furniture dolly, if enough overhead clearance is available.

Larry
Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze
Re: Fuel Pump Replacement Decision
Reply #17 –
I have removed 7 tanks( 15 to 40 gal) in my past using muscle, floor jacks, or the ratchet straps.  The ratchet straps gave me the most control of the tank through the entire process.   With the threaded rod all my muscles ache thinking about is the 15 turns of the nut for 1 inch of travel.
Rodney
1988 Mid Bath
Re: Fuel Pump Replacement Decision
Reply #18 –
I had a leak in the 3" long rubber fuel line "pigtail" at the generator end recently.  Is there a similar "pigtail" outside the fuel tank?  Would this be what should be replaced when the tank is dropped, or the whole fuel line to the generator?  On my 2003 RB the pigtail connected to a white (plastic, nylon, I am not sure) line back to the fuel tank which was then covered by a protective cover.  All that did not look like it would spring a leak as easy as the pigtail with hose clamps.

FYI, I had a problem with my previous 1996 Dodge RV fuel pump.  It would run fine until the fuel got somewhere below 1/2 tank and then not so well-intermitant.  Had I known this I may have saved running it to far backfiring and ending up replacing the intake manifold gasket as well as the pump.


Jay Carlson
2003  LD RB
2005 Bigfoot 40MH35LX
rvingjaygwynne.wordpress.com
Re: Fuel Pump Replacement Decision
Reply #19 –
Jay

"Is there a similar "pigtail" outside the fuel tank?  Would this be what should be replaced when the tank is dropped, or the whole fuel line to the generator?"

The answer is 'Yes'. The pigtail that causes the most grief is the one at the tank which connects to the line running to the generator. I do not know if LD has corrected this issue but at one time the pigtail they used was NOT 'fuel' line but just a rubber hose that they had on hand. Make sure any replacement is certified for 'fuel'.

What I had done, when the tank was lowered, was to replace the entire generator fuel line with stainless steel after the pigtail was replaced with the proper hose.   ;)
Steve S.
Lazy Bones & Cedar
2004 30'IB (Island Bed)
Yesterday is History, Tomorrow is a Mystery
Live for the day!
Re: Fuel Pump Replacement Decision
Reply #20 –
Quote from: Jay Carlson  - 
I had a leak in the 3" long rubber fuel line "pigtail" at the generator end recently.  Is there a similar "pigtail" outside the fuel tank?  Would this be what should be replaced when the tank is dropped, or the whole fuel line to the generator?  On my 2003 RB the pigtail connected to a white (plastic, nylon, I am not sure) line back to the fuel tank which was then covered by a protective cover.  All that did not look like it would spring a leak as easy as the pigtail with hose clamps.
The generator fuel line consist of two pieces of rubber fuel line, with a nylon hardline in between.
If you have already replaced the rubber line, at the fuel tank, you should also change the piece that connects from the nylon hardline to the generator.
LDs, built in the early 2000s, had problems with the generator fuel lines prematurely leaking, LD evidently had a large roll of fuel line that "had" to be used before any new fuel line could be ordered.
Dozens of us have had to drop the gas to replace this $2 fuel line.
Thanks LD.

Larry


Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze
Re: Fuel Pump Replacement Decision
Reply #21 –
I have only replaced the piece at the generator end.  Sounds like both the fuel line to generator and the fuel pump should be replaced if the fuel tank needs to be dropped for either reason.  Maybe even worth thinking about as preventive at near 100k miles, but that sounds expensive.
Jay Carlson
2003  LD RB
2005 Bigfoot 40MH35LX
rvingjaygwynne.wordpress.com
Re: Fuel Pump Replacement Decision
Reply #22 –
My current need is to replace the sections of bad fuel line at each end of the main generator fuel line.  Before I crawl under there in the rain, can anyone say with certainty what diameter replacement line I should get for replacing the short sections at each end?  2000 23.5' FL, and the badge on the fender says "E350 Super Duty".  Just trying to avoid running out for parts with the fuel system half-apart.

Thanks in advance...
Chip
2000 Front Lounge
Re: Fuel Pump Replacement Decision
Reply #23 –
Well, this 2000 23.5' FL may be one of the ones that you can't get to without completely dropping the tank.  Had high hopes, but after prepping some threaded rod for the 'drop bolts', I found a couple of minor details... 

First up, the tank uses bolts on driver side right to the frame, but the passenger side is different.  The tank is not full-width between the rails, so there's an intermediate frame on the passenger side.  That C-section frame faces the main C-section frame, and is close enough you cannot get between them to get at fasteners.  And you'll want to try to get at fasteners, because the passenger side has frame-mounted studs, rather than bolts going into the frame.  So no extended 'drop bolts' on that side.  Max drop on existing studs is about 1.5".  Sadness.

I can photograph the generator feed, but actually getting to it from the front means reaching over all the other hoses, and puts your arm either ahead of the diff, or behind it.  Each has its barriers, so no go, even with the 6" blocks under the wheels for added elbow room.  Attacking it from the driver's side in the back puts you in tank clean-out central.  I might be able to get in if I remove the cleanout hose storage 'tube'.  We'll see.

I'm more likely now to drain and drop the tank entirely -- or drop it enough to access the generator line below frame level. Have a 30-gal 'gas buddy', so that part's easy.  We'll see about the rest.

Chip

2000 Front Lounge
Re: Fuel Pump Replacement Decision
Reply #24 –
Chip, did you already replace the fuel pump for the generator?  The engine's (up front) fuel pump is in the tank but I think the generator's fuel pump is at the generator.  It is for the Microquiet 4000, I am not sure on earlier generators.

If your replacing the engine's fuel pump ignore the rest of my post.
 
If you know you have the bad fuel line yes you need to drop the tank.   But your post sounded like your doing both line and fuel pump because you think the generator's fuel pump is in the gas tank.  The generator's pump, though not a easy to replace, is not technically difficult and does not require removing anything that weighs a lot.  The job is difficult because the pump is buried in the generator compartment below stuff.  Getting to the generator fuel pump can be done with a couple wrenches, sockets and a short extension.  I would consider replacing that before dropping the gas tank to replace the fuel line.
Forgive me if I read your post incorrectly.  Just trying to save some hard work.
John
Currently: 2008 36' Tiffin Open Road
Previously: 2007 Mid Bath