Hesitation when under load-93xlt

[roiddos]

Hello. I am new to forums so please be patient. I have been searching this site and have learned quite a bit, but haven't found this problem yet. Stock '93 xlt starts and runs fine until put under a load and starts hesitating or missing. If I let off the accelerator or mash to kick down it runs smooth. I have purchased a fuel pressure gauge, turn the key on to prime the fuel rail and the pressure only reads about 7-10 psi. If I continue to cycle the key it will get to 40 psi but as soon as I turn the key off the pressure drops to zero. If I start the engine it stays at 40 psi shut the engine off and the pressure drops to zero. I think I am getting fuel in the oil. about two months ago I changed plugs and #5 plug was wet with fuel so I changed that injector oil filter and oil. It did help the hesitation some. Do I have another injector leaking, would a bad o-ring on an injector cause fuel in the oil? With the ice this weekend my wife went back to our reliable '92 sport w/five speed, 190k and still going.

 

[v1rotv2]

My 93' ex was doing the same thing.

Your motor is doing exactly what mine was doing. I had a tune done to see if it would clear the problem, did not work. A few days later I went back to talk to the mech and come to find out he never changed the plug wires. I put new wires on it and it ran like new. I have heard several on the forum state the same thing. Missing and hesitation under a load seems to be the indication of bad plug wires.

 

[roiddos]

Thanks for the confirmation, I have the plug wires and will change them today if the ice lets up. I am still concerned with the fuel pressure fall off and fuel in the oil.

 

[roiddos]

new plug wires work great. Any info on fuel in the oil?

 

[jackieman402]

My Ranger was doing this -- my fuel injectors were dirty. I had them flushed with a through-the-fuel-rail treatment and that fixed it.

Check your fuel filter also. This could be causing the low fp problem.

 

[v1rotv2]

What did you use?

Jackie, what did you use to clean your ejectors and fuel manifold.

 

[btexpress]

There are two items that commonly cause the fuel pressure to drop quickly. Either the fuel pressure regulator is leaking, which would cause some fuel in the oil, or the fuel pump check valve is bad, which requires replacing the pump.

To check the regulator, just remove the vacuum line on the regulator, if it is wet the regulator is leaking.

 

[fordprobegirl]

Running Seafoam through the manifold works great, and its less than $10 a can. Its a lot less expensive than a lot of those injector treatments, and you can do it yourself. Just pull a vacuum line off that feeds into the intake manifold, and start up the vehicle. Get ready on the throttle though, cause u dont want it to die out. Feed the line into the can of Seafoam and the idle will start to drop, just keep revving the truck. don't keep it at one idle speed. If it does die out, it will just take awhile to start up, it has to dry out. This may help a little with your problem as well.

 

[jackieman402]

I used Seafoam first, as described above. It cured probably 90% of the stumbling; then, I used NAPA Fuel Injector Cleaner #2-118489. This comes in an aerosol can which screws onto a special hose; the hose attaches to your fuel rail. This cleared up the rest of the problem.

 

[roiddos]

Thanks for the information. I have run Sea Foam through the intake, and fuel tank. I have also run Lucas fuel injector cleaner. However I haven't done any of that since I checked the fuel pressure. The check valve at the fuel pump seems the most likely culprit if I am not getting fuel in the oil which I am not sure of yet. Forgot, I changed the fuel filter last month.

 

[fordprobegirl]

Hyou checked at all for vacuum leaks? Cause that would be another simple cause for the lack of pressure. Ford put so many vacuum lines on these things, I know my 91 was constantly popping off lines and causing running issues of all sorts.

 

[roiddos]

Yes, no vacuum leaks