1991 Explorer won't start when hot

[drummer]

I have a 1991 Ford Explorer that will run fine until you turn the car off. If the car is at operating temperature and you let it sit for 20 minutes or so the car will not start. If you get there after about 15 minutes it will start, but you have to hold the accelerator to the floor because it acts like it is flooded out. This problem seems to manifest more when the temperature outside is 75 degrees or hotter. It still does it in the winter (I live in Michigan), but you can get it started at any time by putting the accelerator to the floor. I can get it started when its hot by pouring some cool water over the valve covers, but it is still rather annoying. I have done a full tune up and appear to be getting spark, I have replaced the fuel pump in the last year, the fuel relay, the crankshaft position sensor, the throttle position sensor, I cleaned the MAF and the IAC Valve, I replaced the ICM, I have checked all of the vacuum hoses, and know I am stuck. I don't know what to replace next. The car doesn't throw any codes even when it is running rough it gives an all system pass. Please help

 

[MrShorty]

If the car is at operating temperature and you let it sit for 20 minutes or so the car will not start. If you get there after about 15 minutes it will start, but you have to hold the accelerator to the floor because it acts like it is flooded out.

Sounds like pretty classic fuel pressure regulator failure. When you were checking the vacuum hoses, did you pull the vacuum hose off of the FPR to check for gasoline? If not, run the engine for a bit, then pull this vacuum hose and check for gasoline. If there is gasoline in this vacuum hose, the FPR is leaking and needs to be replaced.

 

[drummer]

Do you have some advice on how to get to that vacuum line it is pretty buried in the engine compartment.

 

[natenkiki2004]

It's not super buried, on top of the engine really, just difficult to get large hands in there. Maybe a pair of needle nose pliers would help?

 

[drummer]

I was looking in the wrong place. I just got back from vacation and took a look in my haynes manual. I checked the vaccum line after running the car and there was a black sludge in it? I expected some liquid if it had failed but is the sludge what would be expected for a failed fpr?

 

[MrShorty]

Most cases I've seen reported indicate that it is clearly gasoline (liquid). Certainly over time, I could see it becoming a sludge. The sludge suggests something is getting into the vacuum system that should not be there. Does anything come out of the FPR nipple?

 

[drummer]

Sorry for the late reply but I t s been a crazy week. I replaced the fuel pressure regulator and aat first thought it was finally fixed. The engine started up the first time (instead of the 5th or 6th) and the engine seemed to have more power. But low and behold yesterday I was sitting in a parking lot wqiting for the car to start. Any other ideas?

 

[MrShorty]

At this point, I'd go with the basics -- fuel and spark -- What does the fuel pressure look like when it won't start? Are the fuel injectors firing when it won't start? Are the spark plugs firing when it won't start?

 

[drummer]

I hope to get a fuel pressure gauge on it later this week but I know for a fact it is definitely getting spark the only thing that I don't know about spark is whether the timing is completely correctI also noticed the other day that it tries to do it when I slow down around corners. I don't know if that helps at all but I noticed it. On an unrelated issue my air conditioning compressor won't turn off I don't have the AC on but it keeps clicking is this normal? Thank you for all the help that you're giving me.