Loss Of Fuel Pressure

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MR.7DUSTER3

MR.7DUSTER3

His money, My time
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Anaheim, Ca.
We were out driving the Duster last night to a local car meet and noticed that when the engine gets warmed up we lose fuel pressure. The engine only has 260 miles on it. Let me tell you what we have and maybe you guys can tell me whats up. 360 engine , roughly 400 hp ,holley fuel pump 5/16 fuel line coming from tank,3/8 fuel hose from pump to carb. The reason I know that we are losing fuel pressure is that the engine will stall out at idle and we also have a clear fuel filter ,You can see the fuel just sputtering into the filter. It runs fine when engine is cool only happens after warm. WHATS UP ???

Thanks BOB/ BRYCE
 
Sounds like vapor lock. How close is your fuel line to any part of your exhaust? More HP = more heat.
 
You know I thought about that at first but I checked and it seems that there is plenty of room down by the headers where the fuel line is, But if thats the case what can I do ? I do have a Holley electric pump in the garage .would that help,if I went that route I would have to put a regulator in between right?


Thanks, Bob
 
Mount the pump as close to the tank as possible and as low as you can. Fuel under pressure has a higher boiling point. Good luck and tell us how it works out for you. :)

A regulator is always a good idea. Don't use a liquid filled fuel pressure gauge on the regulator. As they heat up they become very inacurrate and you'll think you're loosing pressure again.
 
Does any body have pics of their set-up, I would love to see them. I'm not real sure on what we are going to do---- Thanks-- Bob
 
before you go through replacing anything, replace your filter element!!!!! if you cant see through element, change it. two fuel pumps, new sending unit sock, only to find out to be a clogged element!!! it did`nt look that bad. I stopped one end and tried to blow through, hardly any air. blew through a new extra and a huge difference. now I replace these soon as they start looking dirty! hope thats all it is.:-D
 
That was i actually replaced first thinking the same thing, Im just worried now that since my son has now even made things hotter back by the fuel tank by removing the tail pipes the hot fuel thing will get worse. I happened to like the way the car sounded before!!!!
 
MR.7DUSTER3 said:
That was i actually replaced first thinking the same thing, Im just worried now that since my son has now even made things hotter back by the fuel tank by removing the tail pipes the hot fuel thing will get worse. I happened to like the way the car sounded before!!!!
Click to expand...

Not sure if the open exhaust would put out enough heat to cause a problem but if it did I'd think a set of turn downs would cure that.
 
Moper, it's a 73 Duster,Will loosening the cap possibly keep it from vapor locking if thats my problem?

Thanks, Bob
 
If I go with the Holley electric pump do I by pass my manual pump or what is the advantages one way or another ?? In the directions on Summit I see it both ways.----Bob
 
If the fuel tank vent lines are plugged (or capped) then yes, as the car runs and the fuel level drops, it creates a vacuum in the tank, eventually matching the suction from the pump. Run it until it loses fuel, then pull the cap. If you remove the cap and get a sucking or whooshing sound (like opening a jar) then it has aventing issue. I see it more commonly in post '72 cars with the vent sytems they had. I even capped a line once thinking the other vents were clear, and got myself stuck the same way... and that is with a big electric pump...lol. Also, sniff your oil to see if it's contaminated with fuel. If the diaphram in the pump leaks, it could be going into the crankcase. You'll smell it and the oil will be very thin if that's the case.
 
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