Electric fuel pump problem

[flatouf]

I have a 1979 Airstream 240. 454 v8, gas engine motorhome.
I'm pretty sure the existing electric fuel pump is itermitent and bad.

I don't know what pump pressure rating is needed for this motorhome.

If I went to Pep Boys and asked for and asked for a 79 Chevy P-30 454 v8 compatible electric fuel pump, would they know what I need?

I don't think so, and That is why I am reaching out to the
Airstream community. Does anybody know the best brand? Pressure needed?
etc.

I know the motorhomes came with mechanical pumps, but since the unit has been retrofitted with an electric pump, I think I want to keep it electric.

If I replace it with the same electric pump, I'm left wondering if it is under pressured or over pressured?

Any help would greatly be appreciated.

[J. Morgan]

You need a low pressure pump, one that makes less than 7 psi.

I recommend a Carter P4070.

[Waipio Rim]

I think that most of us still have the mechanical pump on the motor with an electric pump like the one J. Morgan recommends near the tank to get the fuel to the mechanical pump. Why do you think the pump is bad?

[idroba]

On my '83, 310 when I had it, even the electric rear fuel pump would not push fuel through the in line filter next to the frame rail about mid way, if it were plugged. So, be sure you have a fresh filter, that may be all you need.

[flatouf]

Hmmm! I knew of the mechanical pump, but did not know it also needs an electric pump as well. So now I know the electric pump is sending fuel to the mechanical pump. I spent some time tracing my fuel line from the tank to the electric pump which is located near my steps, and from there to the engine.
However everything is so cramped for space in the engine compartment, I figured the the fuel line from the electric pump went straight to the carburetor and bypassed the old mechanical pump. Apparently it does go to the mechanical pump.

I do have a toggle switch on my dash to turn on the electric pump.
When I purchased this unit from a fellow Air Forum member, he told me the pump switch is used for climbing grades up hill.


This is the second time this has happened in three months.
It will not start. No sign of fuel at the carburetor.

Previously I removed the electric fuel pump, It was making a continuous loud tap, tap, tap noise. There was maybe a tablespoon or less of fuel in the pump bowl, the filter was clean.
I removed the pump. I took my compressor and placed the air hose nozzle and blew air into the inlet of the pump. then took the air nozzle and blew air into the hose comming from the tank. I did two very very short nano blasts, just to push any possible sediment away from the fuel line at the tank.
Put everything back together and the pump worked, the engine started.

When I started the engine for the first time, the pump was making the loud tap tap tap noise until fuel filled the bowl and sent fuel to the engine, then no more noise.

After the initial first start up it makes the continual loud tap tap tap, but was sending fuel to the engine.

Now it makes the loud noise tap tap tap (very anoying) and the engine does not start.

I read that if an electric pump makes a lot of noise the pump could be having problems or is bad.

Also - could there be a lot crap inside my tank? that is blocking the fuel outlet in the tank? My current electric fuel pump filter is clean with no visual debris.

[flatouf]

Previously checked the inline filter as well, was clean but replaced it anyway.

[ScrapIrony-2]

There is also an in-line filter right at the carbureator...small thing...that one is often missed.

[idroba]

I believe that most GM fuel tanks on the P 30 chassis have "fuel socks" on the intake end inside the tank. I understand they are like a bag filter to keep the stuff out of the pickup end. They can become plugged over time. I don't think that there is any way to clean them other than dropping the tank and removal and replacement. The fact that you blew compressed air back into the tank (if I read your post right) may have cleared that sock temporarily.

The clicking of the fuel pump, especially if it cannot pull any liquid into it (which quiets it down) is normal for some kinds of pumps.

Your 35 year old fuel system may just need some big time cleaning.

Or, I may be entirely out to lunch. I am trying to grasp at straws with you.

[Smartstream]

You might try removing the discharge hose from the electric pump and replace with a short hose that you can run into a gas can. Run the pump and watch the flow and sound of the pump. If you have good flow and the pump sounds good look for a problem at the carb or the plumbing to the carb. If the pump is loud with little flow then think about dropping the tank and having it cleaned.

[J. Morgan]

I think the pump taping might be an old A/C Delco solenoid style pump doing what it does when it is running dry.

Two possible problems, the tank outlet is blocked, OR you have a leak in the fuel line between the tank and the electric pump causing it to suck air.

I had forgotten about these old A/C pumps, these last a long, long, time, they are pretty quiet when they are pumping but annoyingly loud when running dry.

With the clatter you mention, the problem is going to be with the stuff between the tank and the pump, (including the tank and the pump).

If the problem were forward of the pump, the pump would quietly run and stop once pressure had built behind the obstruction.

My hunch is that you are sucking air from a rubber part of the line above the level of the tank. Just a hunch though.

[J. Morgan]

I seem to remember a thread about the rubber lines on these motor homes getting pretty rotten after 20, 30, or 40 years.

[flatouf]

Thank You,

To all of my Airstream Brothers who replied to my fuel pump problem.

I will take Morgans advice and replace the old electric fuel pump and go from there.

The last thing I need is a fuel problem somewhere in the middle of the Desert, so I am fortunate that I have the luxury of fixing this problem at home.

I will let you all know when I find out if it is the hoses, tank, pumps or filter.

Has anybody had a problem with gunk in their tank? and if so what did you do to remedy the problem?

Again, thank you so much...

[Vycan]

What desert are you planning on traversing?

[crazeevw]

I'll see if I can't find the thread, but someone posted a very detailed thread about dropping their fuel tank in the Classic Motorhome. If I make the jump to TBI, it's something that I'll definitely have done at the same time.
Good Luck, Derek