HELP

[84sscutty]

fuel pump maybe?...it could be weak and not giving you enough pressure when driving

I'm checking that tonight when I get off work but it supplies fuel fine during driving, WOT, and idling in park or gear as long as it hasn't been driven. Only acts like this after 3-5 miles of driving and doesn't act right again til it's been parked/off for a lil while. I'm completely at a loss. I think I'm gonna start pulling the transmission tonight too so I can try another converter that I have. Don't think it's gonna make it right though.

 

[pontiacgp]

you didn't mention what transmission you have, if it's a 350 I wonder if the modulator's diaphragm is split and when driving you have enough vacuum to suck up some transmission fluid...

 

[84sscutty]

you didn't mention what transmission you have, if it's a 350 I wonder if the modulator's diaphragm is split and when driving you have enough vacuum to suck up some transmission fluid...

It is a 350. I've checked the line at the manifold and there wasn't any fluid in it but I'll double check it tonight.

 

[pontiacgp]

I know bonnewagon already brought it up but is there any way that the fuel is boiling

 

[84sscutty]

I know bonnewagon already brought it up but is there any way that the fuel is boiling

I've thought if that too. Went as far as moving the heater hose fitting too. If I start it and take off without warming it up it still does it just as quick. I take the same route every time and it's the same results every time.

 

[pontiacgp]

well I'm out of suggestions...these engines are usually easy to figure out..

 

[tetomas]

Any chance the lifters were bottomed out when they were initially adjusted? If they were bottomed expansion from heat would tighten up the vale clearence and kill driveability and performance. Put a vacuum gauge on it before it starts acting up, then after and compare the two readings. Acting up after a drive sounds like it is heat related.

 

[84sscutty]

Well I have checked and rechecked everything. Last night I pulled the transmission and changed to converter. I didn't think it would make it right and it didn't. So now I'm convinced there is something wrong internally so out it comes to go back to the machine shop that built it. They have built several engines for me over the years so hopefully it was just an honest mistake.

 

[Bonnewagon]

I'm stumped. Definitely seems heat related but you've changed those usual suspects already. What is the engine temp when this happens? And I would try a different fuel pump, just because. A 305 pump "shouldn't" flood the carb, but...

 

[wrenchbend1]

Heres a long shot , but I have seen this with my own eyes and know it can happen . The rubber hose that goes from the fuel line to the fuel pump , It sits in proximity of the exhaust heat . If the wrong type of hose is used , with the heat of the engine
cause the hose to collapse and "SUCK SHUT" and choke off the engine of fuel. Fuel line is a certain type that has braids in its construction that prevent the hose from collapsing. Say you use a "RUBBER" hose the fuel degrades the integrity and the heat makes it pliable enough to collapse . dont also overlook the possibility of the hose being too short or its routing that creates a
situation that restricts fuel !!!
Good luck with your truck !!!!
Regards

P.S. Fuel tank cap ! Vented or not vented !?!?!?!?!?! when she dies out remove cap check for huge vacuum surge , she
might not be venting and trying to suck the tank to implosion.