Chevy 454 Motorhome engine problems

[Buggs67]

This might be off topic but my motor home has a Chevy 454. Twice now we've been running along fine for a couple hours and it just dies.

Plenty of fresh fuel and it cranks over well.

Towed to a shop ($$$$$) each time and then after sitting overnight or a couple days it starts and runs fine. The first shop was Chevy experts and changed the fuel filter and checked the pressure. They couldn't find any problem. We've logged about 400 miles since then and it happened again.
Sounds to me like vapor lock or intermittent fuel pump failure. Any help??

I know many here are very knowledgeable in all things mechanical.

 

[bigtiller]

Plugged gas cap?.... It happens!

 

[CajunRider]

Check your fuel pump strainer sock in the fuel tank. It is likely plugged with debris and gunk. Overnight it will fill up enough for you to start but as you run the engine hard the demand will overwhelm the supply and the engine dies.

 

[flyerdan]

If it just stops without sputtering or surging, I'd suspect an electrical issue. There is a module in the distributor that is problematic, it could be that it gets hot and opens, and works normally when it cools off enough. Kind of like a thermal switch, although they mostly just quit working altogether.

 

[bigdeano]

What year is it? If it happens again pull a plug wire and use a spare plug to check for spark.

 

[kenmac]

Check your fuel pump strainer sock in the fuel tank. It is likely plugged with debris and gunk. Overnight it will fill up enough for you to start but as you run the engine hard the demand will overwhelm the supply and the engine dies.

I second this....I've had it happen.. Is this mechanical fuel pump or electric ?

 

[Buggs67]

Thanks for the input.

I should have been more specific. It's a 1999 fuel injected model in a Class A. Engine mounted between the front seats. And I assume it's an electric fuel pump.

Both times this has occurred it was on the interstate in heavy rush hour traffic. Barely out of the left lane. My family's safety was paramount concern. If I had the ability to try to diagnose the problem I'd start with some starter spray but the intake is hard to get to.

The first time I had this problem last October it stalled, I threw it in neutral and it started again. Stalled again a couple miles later, restarted, died and then wouldn't start again. My wife figured I ran out of gas, and that kind of how it felt. The garage that time (over an hour from home) changed the fuel filter (which was gunky but not awful) and checked the fuel pressure and all electrical systems. They ran it an hour in the lot and no problem.

I drove it home the long way (1 1/2 hrs) and it was fine. We drove down to PA about 4 hours in April, and it was fine.

Fresh gas in PA and 3 hours later this past Wednesday it died and wouldn't restart.

It's at the mechanic right now and it started immediately when he tried it.

 

[Stimw]

I have owned 2 of them, 1983 Winnie and 1989 Southwind class A's. (both carborated )
There is a fuel pump relay that only works with oil pressure.
BUT, when you turn on the key it will cycle for about 30 sec to allow it to start.
If you have someone turn the key on and off while you listen under the gas tank you should be able to here pump run for short periods.
It could be bad fuel pump relay or bad oil pressure sending unit. (I have had sending units fail on GM vehicles)
Just some places to look.
That 454 will keep up with traffic!
I even had the 1983 up to 85 mph (towing a 23' boat) trying to get away from a semi that kept passing me and slowing down on the next hill! That was back in the late 80's.

 

[kenmac]

I would advise to add an in cab fuel pressure gauge and keep a check on that gauge when you are having these issues.
Sounds like a fuel delivery issue to me.
Of course I'm sitting behind a computer

 

[Sawyer Rob]

I'd be looking hard at the electric fuel pump... They sometimes start to fail just that way...

Can you switch to a different tank, it will have a different pump in it?

SR