Reaccuring problem with 94XLT

[duckdog27]

When my XLT is hot and I turn it off, let it sit for a few minutes, then turn it on and drive, I can't! There is extreme hesitation and no power. I can press the gas pedal all the way to the floor and it won't go over 5mph. I thought I had fixed it by replacing EGR valve and EGR pressure sensor, but obviously did not. I also replaced the Fuel pressure regulator, cleaned the mass airflow sensor, and cleaned the Idle control sensor. I am completely perplexed. It only happens when the XLT is hot. It will start up fine cold and run great until I turn it off and try to turn it back on. Anyone have any ideas? I know there is a lower intake manifold leak (coolant and oil), but could that cause this?

 

[duckdog27]

Any suggestions or ideas would be much appreciated!!!

 

[MrShorty]

Would you classify the hesitation/lack of power as an engine problem or as a transmission problem?
If it is an engine problem, I'd run the computer self-tests (aka pull codes) just to see if the computer can see or has seen any problems. Then check the fuel pressure. Any sign(s) of a blown head gasket/cracked head?
If it's a transmission problem, start by checking the fluid level/condition.

 

[duckdog27]

I check the level of the trans fluid on a regular basis. I changed the trans filter a few weeks ago, but did not do a trans flush. Would a crack head cause these symptoms? It is more like bogging. In park it stutters and if I press the gas pedal it will accelarate rough. When I engage in reverse or drive, the rpms go to below 500, like it is bogging. Then when I press the gas pedal I have no acceleration what so ever. The XLT will just bump and jitter (I don't know how to describe it!) even when I press the gas pedal all the way to the floor. Feels like it is not getting any gas, or a vapor lock of some sort is impeding gas from flowing into the chambers, or too much gas enters through the injectors. I have not clue! This only happens when the XLT is warmed up. Thanks for the response.

 

[Brain]

Is there coolant coming out of the tailpipe? The reason I ask is that you are describing how the '91 XLT I just got in the past few weeks felt and it was because of the cracked head. Here's what happens - the coolant gets hot, gets pressurized and shot into the intake/cylinder...then you have wet pseudo/combustion. When it is cold the coolant is not pressurized so it isn't shot though the crack/leak. When I started out and it was cold it started up fast and had some power....by the time I had driven 15 miles (and stopped six times to add water) it didn't want to start, and when it finally did, it had considerably less power. The time that the engine sits while "off" lets more coolant in through the leak/crack so when you restart, the cylinder(s) is/are more full of water/coolant. That's what I make of it anyways.

If it is a cracked head, make sure to get one that is has the casting "T" on the exhaust port (for all 90-96 4.0L). Also try to get one with the casting number of 93TM-AA instead of 90TM (newer w/ a few less problems). I picked one up today at a junkyard (I pulled it from a '93 Aerostar) for $25. I would have taken both heads, but somebody got there first (but did most of the removal work for me as the intake was gone, valve cover was off, and y-pipe was off of the header). The gaskets are kind of pricy though ($107 at AutoZone for the full set along with $40 for head bolts which you should not reuse). Don't try to fix it w/ stopleak - it is BAAAD stuff (IMO).

Rough idle, bucking like it was in a rodeo...yep - sounds the same.

 

[duckdog27]

I don't believe there is coolant coming from the tailpipe. I will have to check. I know for sure there is a leak in the lower intake manifold gasket. I have to fill the coolant resevoir every so often, but not too much.

 

[duckdog27]

I checked and no coolant dripping from tailpipe. It almost feels as though it does not receive enough gas. Yesterday I was at a mall and went shopping for half an hour and when I returned I could not move the XLT out of the parking lot. It only creeped along, no matter how far I pushed the gas pedal in. Then I had trouble restarting it a few minutes later. It would start up then die, and pushing down on the gas pedal only made it die more quickly. Any ideas what is wrong. Is it something with the fuel system when it is hot????

 

[Brain]

If you think it is fuel related, check the fuel pressure at the rails to the injectors, because if it is good there, then it is good everywhere. If it is bad there, start working backwards - trace the braided hose back and make sure it is not cut/leaking. Replace the fuel filter (few $$). Trace the line back from the fuel filter back to the fuel tank/pump. Check/replace the pump (high $$$$). But first - check the regulated fuel pressure at the point closest to the fuel injectors. There is a pressure tap (looks like a air valve on a tire, black twist-off cover) on the passenger's side of the air intake manifold, between the front and middle injectors. That's where you would hook up a fuel pressure guage to test the pressure. I'm not positive, but I think you can check this in Checker's parking lot with their tools. Just hook up the guage, and then turn the key on to where the fuel pump kicks on a couple of times, take a reading. Then check it with the engine running and the throttle opened up a bit. Another possibility is a vacuum leak between the fuel pressure regulator (sits right in front of the fuel pressure tap) and the vacuum tree (driver's side rear of the intake manifold). It could be a fuel pressure regulator that has gone bad.

Have you checked the plugs/wires/coil pack and engine compression? How about the air filter? Have you cleaned the MAF sensor and checked the throttle position sensor? Sometimes the easiest/cheapest fixes are the ones we overlook. Proper diagnosis and replacement of the broken part(s) is much more effective than guessing and replacing parts all over the place.

 

[4544x4]

My 96 xlt did the same thing and it was the fuel pump.it would supply 10-15 psi enough to make it run(barely)replaced fuel pump now it works great.

 

[duckdog27]

The truck runs great when I start it up in the morning. It only acts up when it has been running for awhile and I shut it off. I don't know much about cars, but I know it has to be something located around the engine which can be effected by heat. I pushed that little tire nozzle to test the fuel pressure and gas sprayed right out. The problem is I obviously cannot test it when the car is hot and acting up.

 

[4544x4]

The truck runs great when I start it up in the morning. It only acts up when it has been running for awhile and I shut it off. I don't know much about cars, but I know it has to be something located around the engine which can be effected by heat. I pushed that little tire nozzle to test the fuel pressure and gas sprayed right out. The problem is I obviously cannot test it when the car is hot and acting up.

Ok I'll cover this once more....
My 96 XLT did the same thing.When hot shut it off and thats it.It is the fuel pump!!!!!Check the fuel pressure with a guage not a stick.It should be 35-40 PSI.I'm sure you will find that when it acts up the pressure is low.I'm ASE cert,I've had the same problem.Listen to Brian he seems to have good advice.and Checker should let you use a guage.Sorry to Be an A@#hole.BAD DAY.I am sorry.

 

[Brain]

"I'm not positive, but I think you can check this in Checker's parking lot with their tools. Just hook up the guage, and then turn the key on to where the fuel pump kicks on a couple of times, take a reading."

Having it spray out doesn't mean that it has enough pressure to work with the fuel injectors. These engines don't have carbs, so they require more than the 5-15 psi that carbs work with. You NEED a guage to diagnose this problem, not a flaming engine compartment. Pumps are expensive....do the ten minute diagnosis before replacing it. I would make sure that is the problem before I spent over $100 on part - and a B*^$% of an install - but maybe that's just me (I don't have many $ to throw at guesses).

 

[duckdog27]

Thanks, I really appreciate the advice. I'll have the fuel pressure checked out, but I've never heard of Checkers. Must be located only in the South!

 

[4544x4]

checker,kragen,shucks all the same

 

[anthonytony]

fuel pump....

 

[Brain]

http://www.partsamerica.com
That's the combined website of Checker/Kragen/Shucks and Advance Auto Parts. There's also Napaonline.com and Autozone.com.

 

[cfkane]

Are you by chance running Ethanol blended fuel? 10% Ethanol has a knee in the distillation curve that often results in a vapor lock when the vehicle sits for 20 – 120 minutes.

Another possibility is the fuel tank vapor return line. If the Canister Purge Solenoid is not working correctly the fuel tank will develop a vacuum that works against the fuel pump. A second possibility is the Vapor Canister being plugged, not as likely but still a possibility. A quick test for both is to crack the filler cap slightly and see if a pressure or vacuum condition exists.

Another aggravating factor in all of the cases is a low fuel volume in the tank. See if the problem is worse when the tank is low. That will help determine if the condition is fuel related. In reality it could be all or a combination of the conditions.

 

[duckdog27]

I run regular 87 octane from Mobile stations in the XLT. I don't know the ethanol content in it. I forgot to mention that if I drive for awhile, say on the highway for 30 minutes and pull at a rest stop and leave the car running for five minutes it will act up, not to the extent that it does when I turn it off, but when I press on the gas pedal it bumps and hesitates. Could this be related to the fuel pump also? Your info is wonderful. I can't do anything now with the truck b/c I'm laid up in bed after surgery. But I'll let you know after I get it checked out by a technician. Thanks again.

 

[4544x4]

I run regular 87 octane from Mobile stations in the XLT. I don't know the ethanol content in it. I forgot to mention that if I drive for awhile, say on the highway for 30 minutes and pull at a rest stop and leave the car running for five minutes it will act up, not to the extent that it does when I turn it off, but when I press on the gas pedal it bumps and hesitates. Could this be related to the fuel pump also? Your info is wonderful. I can't do anything now with the truck b/c I'm laid up in bed after surgery. But I'll let you know after I get it checked out by a technician. Thanks again.

yes it still will act up.anyway mine did.

 

[duckdog27]

The last few times I have driven the XLT and stopped, turned it off for a while and then attempted to restart it, the truck will start up for a bit then die. I have to sit for a minimum of 30 minutes until it will restart. Do think it is possible for your weekend mechanic to replace a fuel pump? And do you recommend that I purchase one from Ford and not a after market part from Autozone or Napa? THanks again.