engine cus out when hot, no fuel pressure
Thread Starter
4th Gear
Joined: Aug 2003
Posts: 4
Likes: 0
From: middletown n.j
engine cus out when hot, no fuel pressure
My 85 (115,000 miles) has just started to give me a problem where she stalls out when hot over 200 degrees. She will not startup until it cools down. No check engine lite. I started by changing the ingition module, coil and cap. The fuel pump was changed about 1 1/2 years ago. After installing the parts the engine started up fine then died when it got hot. I pull the pump checked for volatage at the pump, lite when on then out, so I changed the fuel pump relay.(fuse is ok). I attached the pump to the battery and it spins, so do the blades. Just to make sure I changed the screen, reassembled everything. Car starts then it died when it got hot, again no fuel pressure. I jumped the relay its working, I jump power to the ALCL (g) test lite goes on. Anybody have any ideas (I also changed the fuel filter the same time I put the pump in last year. When its running the fuel pressure is about 35 lbs.
Team Owner
Joined: May 2002
Posts: 24,337
Likes: 25
From: San Diego , CA Double Yellow DirtBags 1985..Z51..6-speed
Re: engine cus out when hot, no fuel pressure (joesc4)
Perhaps a pinched or restricted pickup is causing the fuel pump to starve for liquid, and has a lower suction pressure than normal.
When fuel (or any substance) is hot, it doesn't take as much vacuum to boil it (it raises the vapor pressure).
Everyone will say vaporlock is impossible on a EFI car, but I disagree. My Ford has vaporlock, I thinnk... and it's fuel injected.
Have you ever run the vette dry of gas?
When fuel (or any substance) is hot, it doesn't take as much vacuum to boil it (it raises the vapor pressure).
Everyone will say vaporlock is impossible on a EFI car, but I disagree. My Ford has vaporlock, I thinnk... and it's fuel injected.
Have you ever run the vette dry of gas?
Thread Starter
4th Gear
Joined: Aug 2003
Posts: 4
Likes: 0
From: middletown n.j
Re: engine cus out when hot, no fuel pressure (CentralCoaster)
Thanks for the reply; I was thinking of vapor lock myself. Yes over the winter I had the car painted and it was in the shop for two months. The gas dried up but it did run dry. Any way I just replaced the screen when I pulled the pump to see if it was working. I just spoke to someone who suggested that when it stalls out again to pull the plug off the oil sending unit (two tabs) and jump the plug with a wire, if I get fuel pressure, its the oil sending unit. The second thing he suggested was to pull the computer down, leave it plugged in, start the car and heat with a hair drier, if it stalls, then its the computer. I don't know I have try this stuff out.
Team Owner
Joined: May 2002
Posts: 24,337
Likes: 25
From: San Diego , CA Double Yellow DirtBags 1985..Z51..6-speed
Re: engine cus out when hot, no fuel pressure (joesc4)
that oil pressure switch is in parallel to the fuel pump relay. This means, either can supply the fuel pump with power. The oil pressure switch is closed at 4 psi.
Shorting the fuel pump switch connector would force the pump on.. if this works, it means your ecm control or fuel pump relay is bad.
This oil pressure switch IS NOT a low-pressure safety cutout for the fuel pump. It IS NOT hooked up in series with the fuel pump relay.
Shorting the fuel pump switch connector would force the pump on.. if this works, it means your ecm control or fuel pump relay is bad.
This oil pressure switch IS NOT a low-pressure safety cutout for the fuel pump. It IS NOT hooked up in series with the fuel pump relay.
