1994 f150 5.0
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Junior Member
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1994 f150 5.0
1994 F150 5.0
Truck cranks and runs great when engine is cold goes into gear smoothly. After about 10 minutes it starts to idle up and when I rev the engine it spits black liquid out the exhaust and when I put it in gear it stalls. After that it won’t crank up unless I unplug the fuel pump relay, it runs for about 15 seconds then dies. When I try and plug the relay back in it dies almost immediately. If anyone has any idea please help me, personally it makes no sense to me.
Truck cranks and runs great when engine is cold goes into gear smoothly. After about 10 minutes it starts to idle up and when I rev the engine it spits black liquid out the exhaust and when I put it in gear it stalls. After that it won’t crank up unless I unplug the fuel pump relay, it runs for about 15 seconds then dies. When I try and plug the relay back in it dies almost immediately. If anyone has any idea please help me, personally it makes no sense to me.
Senior Member
Joined: Jun 2016
Posts: 180
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From: Grenada Mississippi
Really does not make sense. I would start checking things, starting with a fuel pressure test that includes how long it takes the fuel pressure to drop to zero after the key is turned off. meanwhile I will try to think of anything else. I wouldn't say the black liquid is normal, but I do believe the part ethanol fuel causes it to make a little water. I read that somewhere a while back, and my 96, 4.9 always makes a few drops when idling a few minutes. the front of the muffler will drip too.
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Junior Member
Joined: May 2020
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I blocked off the egr valve with a tin can and it’s running great now.
Really does not make sense. I would start checking things, starting with a fuel pressure test that includes how long it takes the fuel pressure to drop to zero after the key is turned off. meanwhile I will try to think of anything else. I wouldn't say the black liquid is normal, but I do believe the part ethanol fuel causes it to make a little water. I read that somewhere a while back, and my 96, 4.9 always makes a few drops when idling a few minutes. the front of the muffler will drip too.
Senior Member
Joined: Dec 2006
Posts: 43,526
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From: Joplin MO
Either the EGR valve is sticking open, or it's being commanded to open when it shouldn't. There should be no vacuum on the line to the EGR valve at idle. Clean the EGR valve, reinstall it, but leave the vacuum line off and plugged. If it runs bad, replace the EGR valve. If you have vacuum at idle, you have a problem with the EGR valve control solenoid/motor, EGR valve position sensor, or the DPFE.