Community Forums

nchappycampr · 07-12-2016, 03:16 PM

Hi All,

New to the Class A world. Bought a really nice, well maintained Newmar Dutch Star with a Chevy 454. Have done a bit of searching and discovered that our fuel pump failed right about when it was supposed to,

right around the 50K mile mark. Naturally we had just filled the tank before going to the lake.

The good news is that it failed in the drive way just after we pulled in at home

.

What I want to know is:

1) can you put an external fuel pump on and not replace the in-tank one? Pros and cons?

2) if you can't do the external pump, how do you go about accessing it through the floor?

I'm not afraid to do this myself (with help) but would REALLY rather avoid having to drop the blasted fuel tank.

Thanks in advance for any help you can offer.

BFlinn181 · 07-12-2016, 04:32 PM

While some folks have cut a hatch in the floor over the fuel tank, I'd really suggest draining and dropping the tank. With the tank out, you can not only replace the in tank pump, but also inspect the tank interior and replace fuel lines for the engine and generator.

jacwjames · 07-12-2016, 08:09 PM

I just changed the fuel pump in my Suburban, it didn't fail but I had trouble starting it and suspected a failing pump. I dreaded doing this but in reality it wasn't a bad job. I backed the Suburban up on some ramps for elevation and worked through dropping the tank. Luckily I was able to run most of the fuel out, ended up with less then 5 gallons in the tank so it was fairly lite. I disconnected the fuel lines and wiring harness for the pump. Pulled the tank out and and cleaned the top good before taking the pump out of the tank. Went back with new pump and reinstalled in reversed order. Took me about 2.5 hours to do the job.

I had done some research on doing this, found a couple Youtube videos that helped. Also found a video showing cutting an access hole to replace the pump. One issue is not knowing exactly where the pump is located on top of the tank and how the fuel lines and wiring harnesses are run. Getting everything clean would probably be more difficult. It is possible but I don't know if it would save you any time.

Darrel · 07-13-2016, 11:43 AM

I would seek another diagnosis. Most failing fuel pumps exhibit problems on the road under heavy load usage. If you just filled with fuel I might suspect and/or change the external fuel filter first.

Have nice day - Darrel

BA-in-Mich · 07-13-2016, 03:06 PM

I dropped mine last fall, used a harbor freight hydraulic table. The tank was half full but the table can handle 1000 lbs. I did have to jack up one side of the motor home about 3 inches to roll it out but it was very doable. I replaced the fuel pump and all of the hoses above the tank so as if I have a problem on the road I'm able to access the rest.

Hooligan · 07-13-2016, 03:33 PM

Dropped 90gal RV gas tank years ago. Got the fuel as low as possible. Used a floor jack and 3/4 plywood. Tank was held by 6 long bolts, replaced one at a time with allthread. Moved nuts down the allthread a few inches at a time and lowered the tank enough to get to the top. Only replaced wiring but would have had room to replace a pump. That RV had external fuel pump.

If the tank has fuel, it can get out of hand it it is tipped so the fuel sloshes while lowering -without support to the frame..

You asked about external pump, pre-fuel injection engines had external but don't know if external can pull thru the pump in the tank or if it can develop the pressure you need...

RickNC · 10-02-2023, 11:21 AM

When I replaced the carpeting in our motorhome (1995 P30) I cut out and installed an access panel over the fuel pump. I carry a spare pump.

If you do this you have to carefully seal the edges of the cutout in the Subfloor or subsequent water intrusion is going to make short work of destroying your subfloor.

Jim_HiTek · 10-02-2023, 11:35 AM

Quote:

Originally Posted by RickNC

When I replaced the carpeting in our motorhome (1995 P30) I cut out and installed an access panel over the fuel pump. I carry a spare pump.

If you do this you have to carefully seal the edges of the cutout in the Subfloor or subsequent water intrusion is going to make short work of destroying your subfloor.

FYI: Racing experts and posters here on iRV2 mentioned that the fuel pumps are not a 'carry a spare' item unless they are carried in something where they can swim in fuel. The seals dry out, crack, and break apart after a short period if they aren't. And it's obvious that since having a pump in a container filled with fuel while traveling wasn't smart either, that it's better to just depend on good luck and automotive parts stores to carry something universal instead.

Jim_HiTek · 10-02-2023, 11:45 AM

Quote:

Originally Posted by nchappycampr

Hi All,

What I want to know is:

1) can you put an external fuel pump on and not replace the in-tank one? Pros and cons?

2) if you can't do the external pump, how do you go about accessing it through the floor?

I'm not afraid to do this myself (with help) but would REALLY rather avoid having to drop the blasted fuel tank.

Thanks in advance for any help you can offer.

I put an external fuel pump from Summit Racing in the fuel line around 4 feet from the Cummins engine's lift pump. The tank was 20 feet forward between the front wheels. It was a diesel external pump. There it stayed and worked fine for 12 years. I attached it to the inner frame rail of the chassis to prevent any road debris from damaging it. Found the ignition wire up on the engine.

External fuel pumps for gas are used all the time for race cars and I've used them on personal cars...they just suck gas through the internal pump so the old pump stays in place.

Yes, they work, and work fine. Saving lots of time and money. Not to mention difficult work.

RickNC · 10-03-2023, 09:26 AM

Quote:

Originally Posted by Jim_HiTek

FYI: Racing experts and posters here on iRV2 mentioned that the fuel pumps are not a 'carry a spare' item unless they are carried in something where they can swim in fuel. The seals dry out, crack, and break apart after a short period if they aren't. And it's obvious that since having a pump in a container filled with fuel while traveling wasn't smart either, that it's better to just depend on good luck and automotive parts stores to carry something universal instead.

Lots of experts, few with first hand knowledge. Ever bought a fuel pump? They are not pickled in gasoline. Is there a expiration date? I haven’t seen one in the 50 years since I first laid hands on a fuel pump. A new car or truck is built. It can set on a lot or ride on ship for months with less than a 1/4 tank of fuel in it.

The concern about gaskets and seals drying out perhaps was valid 30 years ago, but no one is using natural rubber seals or paper gaskets on gasoline fuel systems today. The concern with modern fuel pumps is premature electrical failure from extended operation with low fuel levels.

If you want to rely on internet experts advice and parts supplier luck, that is your choice.
Personally I prefer to rely on experience and preparation.

Ericjump · 12-01-2023, 02:06 PM

I am considering buying a 1997 Winnebago Adventurer with chevy 454 engine. It has been sitting for several years. I have several questions relating to the fuel system. With a fresh battery I can get the engine to turn over but not start, I can get it to start by introducing starting fluid through the intake system. I have just started it for a few seconds at a time. Is the fuel pump electric? and where is it located? Should the fuel pump activate when the key is turned on? where is the relay for the fuel pump? Thanks in advance for the help, I'm an aircraft mechanic so I can work on the system if I know what I'm working on. please reply to my email address. ericjump@aol.com

SteveJ. · 12-01-2023, 02:41 PM

Quote:

Originally Posted by Ericjump

I am considering buying a 1997 Winnebago Adventurer with chevy 454 engine. It has been sitting for several years. I have several questions relating to the fuel system. With a fresh battery I can get the engine to turn over but not start, I can get it to start by introducing starting fluid through the intake system. I have just started it for a few seconds at a time. Is the fuel pump electric? and where is it located? Should the fuel pump activate when the key is turned on? where is the relay for the fuel pump? Thanks in advance for the help, I'm an aircraft mechanic so I can work on the system if I know what I'm working on. please reply to my email address. ericjump@aol.com

Assuming the multi port injected engine.

There are 2 relays. The first should fire the fuel pump for about 2 seconds when the key is turned on. The other operates from an oil pressure sender. When pressurized the circuit to the fuel pump is energized. A multi meter and/or a second set of ears are your friends.

jaydee325 · 12-01-2023, 04:01 PM

Just do it right. Transfer the fuel from the tank to other vehicles or temporary storage. Drop the tank and replace pump as well as all other accessible rubber parts. You'll be good to go for a long time with no worries if shortcut repairs will last.

SteveJ. · 12-01-2023, 04:21 PM

At 26 years old one could assume the fuel pump is about done, assuming it still works. That said, I replaced mine, also in a 97 with a Delphi and it failed at 14 months.

BTW, be very careful pulling the assembly from the tank as they are pretty much made of unobtainum for the 60(and 75?) gallon tanks, '97 and earlier. Starting in '98 they went to a plastic top plate on the assembly. I reused the old assembly, replacing the pump on it. Don't forget to obtain a new sock filter for it along with a fresh external filter. Both the Delphi and the O'Reilly unit came with new tank gaskets.

I never really followed up on installing an external pump as I created a hatch in the floor that gives me easy access to the wiring, pump and hoses. That hatch came in handy when the Delphi pump quit working on a trip, all of the work was inside instead of out in 40* and rain under the coach in the dirt on the side of skinny and windy AR Hy7 north of Hot Springs. O'Reilly's had a pump in stock, easy peasy.