I have posted this question before but have done some more investigating since and want to get some opinions. I have a 28 dodge gasser pickup with 383 sbc stroker, aluminum pro comp heads, tunnel ram, 2 450 holleys, etc. I just finished the car this winter and have had it on the road for about 6 weeks. The problem is after it has been driven and warms up, then sits for 10 minutes, you cannot start it. I installed an inline fuel gage on the fuel line. By the way it is a mechanical pump. Yesterday I did some experimenting and drove it hard for about 5 miles. It maintained 5-6 PSI the whole time. I shut it off and turned it on several times. Afterwards, I let it set for 10 minutes and then came back and the fuel pressure was 1 psi. I could not start the car. I let it set for 2 more hours and then it started good and had 5 psi again. Obviously this is a fuel problem but what is it? Is it the dreaded vapor lock? Or is it a weak fuel pump? I am inclined to switch to a holley electric pump. Any ideas?...
So it sits for awhile and gets down to 1psi, then it won't start. Have you checked the gauge after trying to start it? Does it get back up to 5-6 psi even if the engine won't start?
If you think its a fuel problem,shut your pump off few minutes before you shut it off.If you are loosing lbs may be a float valve.problem.
sounds like vapor lock. is any portion of your fuel line to close to headers or laying to close to the engine?
It's not unusual for the pressure to drop after sitting a few minutes and its possible that it could be the fule pump , but why wouldn't there be enough fuel in the carbs to fire it? That's got me wondering about the carbs. I run 2 Edelbrock 500s at 4 1/2 lbs. and mine drops to 0 after about 5 minutes but starts on the 1st turn almost every time. Hope you get it figured out and let us know
If it's the truck in your avatar, I can't imagine the headers getting your fuel system too hot. When it does finally start again, after a few hours, does it fire right up or does it need to pump fuel for >15 seconds, as if it's filling the bowls with gas again? I don't know anything about multi-carbs but does it run off of one of them until your throttle opens a certain amount? If so, pull one of the bottom fuel bowl bolts off of the primary carb (on each bowl) to see if there's fuel in there (but be ready to catch it with a cup of some sort). Might be leaking into the engine or something.
It is the truck in the avatar. It fires right up after 2 hours, no hesitation. Runs off of both carbs with no progressive linkage.
Do the obvious. Put a loop-reading ammeter on the positive battery cable when you attempt to crank it. If the starter draws 200 amps (or more) you have a starter with excessive resistance. You may need to replace the drive end bushing (in starter) or rebuild the starter 'proper'. Also check for excessive heat (ambient temp) warming the starter. I see your headers are above, but if the starter has excessive resistance it will be aggravated by just a small amount of heat. Also, inspect battery cables. GOOD CLEAN attachment points, good engine to frame ground, (are the cables heating up when cranking?) Check these points, and please let us know.
Do you have spacers between carbs and manifold ? The fuel may be percolating and thus the hard start problem you are facing. You might want to put a set of phenolic spacers in there.
+1 I think this is it. Make sure the floats are not too high any percolating on a high float will make it worse.
When trying the no go hot restart do you have both fuel and spark? If so it is possible one of the carbs has lost it's fuel into the engine and flooded the engine.
Its hard for me to understand that it needs spacers if it already has a tunnelram. Isnt this a HUGE spacer? Maybe I am thinking about that wrong.
next time you let it sit and it want crank hold throttle to floor as if flooded see if it cranks .if carbs have gas in bowls fuel pressure doesn't matter????sounds like its flooding out.
If you think that the fuel is flooding the engine from heat expansion, drive it long enough to cause the problem and pull the aircleaners after you shut it down and look down into the carbs. If either carb is flooding, you will see wisps of smoke coming from the offending carb/carbs. You may need to lower the float level if this is the case.
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