1994 Ford F-150 idling and then stalling

PORTHOS1

MEMBER
1994 FORD F-150
V8
2WD
AUTOMATIC
125,000 MILES

I am not getting any response from my first post I paid for so I will try someone else. I have an issue where the truck starts up fine and runs. And after a few minutes the idle starts loping or slowing down then sometimes it corrects itself and idles normal. Then back down to wear it is barely going. The last mechanic told me to clean the MAF sensor which I did and also check the TPS and it was good and also clean the egr valve. I replaced it cause it was so old. No different. I had previously replaced the IAC before contacting you guys.

Now here is what I have found since then. The plastic vacuum hose that went to the fuel pressure regulator was 3/4 broke in one spot and barely hanging on and cracked in another. So I quickly replaced it and same issue. My question is with the hose being broke and cracked for awhile make the regulator not work properly and now its bad? Cause after I have fixed the hose and put it on, the ilde made no difference. Even with problems I am having you would think that should at least make some sort of noticable difference.

3 Replies

RACEFAN966

MECHANIC
5,029 POSTS

Ok to answer your question it may not make any difference depending on what all it causing the idle to surge. Now you say you checked the TPS and it was good so did you check the reference volts to see what it is telling the computer? Have you checked or changed the O2 sensor? If the O2 has 125000 on it too then it is over due for changing should be changed about 80000. Have you used throttle body cleaner and cleaned the throttle body out? Get back to me and we will see what we can do.

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Wednesday, September 1st, 2010 AT 10:12 AM

PORTHOS1

MEMBER
49 POSTS

Tps sensor is in the paramaters that the book says. I have cleaned the throttle body also. I just put my gas pressure gauge on to check the pump and the regulator. All check out fine. And the o2 looks a thousand years old. When I would drive it before this happen the check engine light would come on and go off. Now when it dies the check engine light is on. Should I just spend the money to buy the code reader for the 1994 vehicle I have?

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Friday, September 3rd, 2010 AT 10:31 AM

RACEFAN966

MECHANIC
5,029 POSTS

So what is the fuel pressure? What was the reference voltage that the TPS sent to the computer? I ask these questions because it does matter and this way I can look them up to see if it is in spec so I can better help. As for spending money on a scanner no don't here is how to do the same thing with a test light and paper clip then you turn the key on and count the blinks on the test light ok. Let me know what the codes are. So where you see the volt meter put a test light there instead. Now where you see the spout connector and the data link is where you use the paper clip to link the spout connector to the data link together like a jumper. Now turn the key on engine off. The test light will blink once and short pause then blink twice (code 12) now longer pause and then it will blink again and short pause and blink again and longer pause. Now if it blinks twice then say once that is code 21 and so on.