Fuel problem

[Potomac Valley Organics]

Latest in the saga of Olive.

1977 Dodge M880...

Cleaned out fuel tank, new sending unit, new rollover valve, new mechanical pump, new steel fuel line. New Holley 600 CFM 4 Barrel

She chokes out after about a mile if you rev the engine. Pop the hood, and the fuel filter is bone dry. Been through three mechanics. Disconnect the fuel line from the pump and blow air back into the tank. Reattach and she pumps. Also, connect the fuel pump to a five-gallon can of gas and she pumps. So I thought maybe there was gunk in the tank or the line, hence the cleaned out tank and replaced fuel line.

Removed gas cap to make sure she vents. Same problem: she'll idle and rev holding still, but gun her on the highway and she'll choke. I think the blowing air back into the tank was a red herring; it seems that time was let her fire again.

So now I'm thinking the manifold is heating up the fuel line and I'm getting a vapor lock. I want to try a heat shield to test it out, but I thought I'd run the scenario by you fine lads before I did. One mechanic thinks it may be a bad fuel pump eccentric (cam), and wanted to put an electric pump on. That does not compute for me since the truck fires back up after sitting still for ten minutes.

It is true that there's only about six inches between the manifold and the fuel line, but it does not account for why this is happening. The engine compartment does not seem overly hot. Any thoughts'd be appreciated.

Thanks,

Will

 

[Bob H]

Could be vapor lock.
Radiator Hose?
I eliminated the metal line that runs up to the carb, allowing me to run the rubber line away from heat sources.

Yet perhaps there is a restriction between pump & tank which is limiting flow and when revved up on the road, she sucks the fuel right out of the filter.
or Possibly sucking air at the top of the sending unit thereby reducing flow.

But!
a 600 CFM 4 barrel is way too much for that 318 with those tiny little heads.

 

[Potomac Valley Organics]

Could be vapor lock.
Radiator Hose?
I eliminated the metal line that runs up to the carb, allowing me to run the rubber line away from heat sources.

Yet perhaps there is a restriction between pump & tank which is limiting flow and when revved up on the road, she sucks the fuel right out of the filter.
or Possibly sucking air at the top of the sending unit thereby reducing flow.

But!
a 600 CFM 4 barrel is way too much for that 318 with those tiny little heads.

Thanks for the reply.

My lines between pump and carb are rubber, too.

I think I've eliminated all obstructions between the tank and the pump that could limit for except for that rollover valve, which I may take out next.

What do you mean "sucking air at the top of the sending unit thereby reducing flow?" That's an intriguing idea; how would that happen?

As to the carb, bowls are adjustable and I cant see that being the prob since the carb doesnt "demand" so much as the pump eccentric pumps faster the higher rpm.

 

[Potomac Valley Organics]

Sell Olive?

I love this truck but, at some point, I need a truck that works consistently (see http://www.steelsoldiers.com/showthread.php?125380-Fuel-problem).

Where would I look to toy around with the idea of selling her/how to value her? (EDIT) I.E., to get an idea of the value, etc.

 

[NDT]

My 880s have never vapor locked ever using the stock metal tubes. And it is HOT here. I have filters before and after the mech fuel pump to protect the valves from debris.

 

[Potomac Valley Organics]

My 880s have never vapor locked ever using the stock metal tubes. And it is HOT here. I have filters before and after the mech fuel pump to protect the valves from debris.

Yeah it seems like a stretch to me, too. However, there is no debris in the fuel system at this point, so I'm at a loss.

 

[NDT]

I would put a gas can under the hood on the passenger side and connect to the pump and go for a spin. That will eliminate the tank, or not. Don't sell the truck, you are missing something simple but hidden, once you figure it out, the 880 will be super reliable.

 

[Potomac Valley Organics]

I would put a gas can under the hood on the passenger side and connect to the pump and go for a spin. That will eliminate the tank, or not. Don't sell the truck, you are missing something simple but hidden, once you figure it out, the 880 will be super reliable.

Have done that and she draws fine. Problem seems to occur on high demand/rpms.

 

[Coffey1]

Scrap price to 20k it's up to you.
But a running drivable truck will be worth more.

 

[ke5eua]

I agree something simple overlooking.

While not a 880, I had a '82 dodge w150 with the 318 and loved her. I had some fuel issues and ended up putting a electric pump inline with the mechanical to prime and keep demand.

Grandfather bought her off the lot in '82 and gave her to me about 5 years ago. She died peacefully last year, she will be missed.

 

[Potomac Valley Organics]

I agree something simple overlooking.

While not a 880, I had a '82 dodge w150 with the 318 and loved her. I had some fuel issues and ended up putting a electric pump inline with the mechanical to prime and keep demand.

Grandfather bought her off the lot in '82 and gave her to me about 5 years ago. She died peacefully last year, she will be missed.

Well lads, i took the rollover valve out of the fuel line. And i dont know if it was that or my threat of selling her, but no problems so far!

 

[ke5eua]

Well lads, i took the rollover valve out of the fuel line. And i dont know if it was that or my threat of selling her, but no problems so far!

Good to hear. Sometimes a good scolding will set them straight for a little bit, lol

 

[dtracy22]

I know you mentioned that you removed gas cap, but was it left off while it was being driven. I had a car once that the gas cap wouldn't vent and it did what your truck was doing after just a few miles down the road

 

[Potomac Valley Organics]

I know you mentioned that you removed gas cap, but was it left off while it was being driven. I had a car once that the gas cap wouldn't vent and it did what your truck was doing after just a few miles down the road

Yeah, I had it off while driving to make sure she was venting. She still choked. Seems like removing the rollover valve solved the problem, after all. Maybe she was suckin' hard enough to pull the little ball bearing up into the fuel line?

 

[Coffey1]

I could make comment on that but I won't but she might be a keeper lol

 

[Potomac Valley Organics]

I could make comment on that but I won't but she might be a keeper lol

Haha aye