Help with complex running problem!

[Jet Ski Puller]

I'm having problems with my '94 while pulling my 1500 lb (light) jet ski trailer. After it has been running for a while, it will start to hesitate and sometimes the 'Check Engine' light comes on. It is running really hot, and is low on power. The temp gage seems normal, but the cooling system is working overtime to try to keep it cool. The fan clutches in constantly clear up to high RPM's., and even when slowing down, the computer will keep the idle a little high with the fan clutched in for 10 - 20 seconds. So, don't think it's a thermostat, or cooling system problem.

I'm suspecting the hesitation may be vapor lock due to the excessive heat.

Cleaned the MAS sensor recently. Thought it may be the MAS, but disconnected it and went into 'limp home' mode and it made no difference.

Replaced the fuel filter. Fuel pressure is good, but couldn't check under load.

A mechanic buddy of mine downloaded the codes from the computer, and there was a rich condition in Bank 1, AND a lean condition in Bank 1 recorded (seems strange to have both). There was also a purge canister fault code, and we're suspecting the relay switch...don't think that has anything to do with it, but will fix that. We checked out all the sensors (TPS, O2, MAS, etc) All seemed to be functioning properly, but we could only test in the shop when it was hot, not right when it happened under load out on the freeway. Checked everything else the 'Snap On Scanner' is capable of, and everything checked out normal.

Only other possibility we can think of that could cause all of the above would be a plugged CAT. But, it only has 74K on it, so that seems unlikely. Anyone know of a way to test for this?

Any ideas on what could cause me to be down on power, run really hot, and create a rich and lean problem in the engine?

Thanks.

 

[JDraper]

I know you said you don't think it's your cooling system, but you might have either a water pump going, or a clogged radiator. Either of those would cause you to overheat, which would kill the performance.

 

[theofile]

I've got the same problem with my '94Explorer. Please let me know when you find out what it is, and I'll do the same. Thanks.

 

[theofile]

Have you seen this post which may refer to this problem. Ira describes a problem with the fuel pressure regulator that seems to give rich and lean messages?

Dead Link Removed

 

[oahrens]

Hey JSpuller,

I was having exessive loss of coolant and running hot after 5 miles. I replaced the thermo and temp sensor and pressure checked the radiator. I think it was a water pump issue because there was no leaking. I threw in prestone sealer and voila. That's the cheapest and easiest thing to try.

I also had the infamous bogging/check engine/ no power/ poor mileage at about 75,000 on my 91. After the tune up, fuel filter, O2's, MAF, and FPR it turned out to be clogged cats. The only test that I did was at higher RPM's felt the exaust and assumed that there should be more.

BTW- my codes were the same as yours (rich/lean)

 

[Chris Jella']

I had similar problems this weekend, but without tripping any codes, no check engine light and tried to pull them and got nothing. If I figure anything out, I'll let you know

 

[oahrens]

hey chris...

are you stationed out there?

 

[theofile]

Jet Ski Puller,

Over the last 2 days, I put in new plugs, flushed the cooling system, put in Mobil 1 trany fluid, put in a new fpr and cleaned the sensor element in the MAF. I tested the truck this evening and ran it hard, pulling a 3500 lb boat and trailer. I had lots of umph and never bogged. The ambient temp was 80 and the temp gauge never went above 1/3. The check engine light never went on. Tomorrow I'm taking the fully packed boat and rig on a 80 mile drive to Lake George. That'll be the real test. I'll report what happens when I get back. Right now it's working great but I don't know what did it. None of the above was very expensive. .

 

[TerraBomb]

ok here's what an buddy of mine did :

took off the cltuchworks and the fan...replaced it by an electric fan...

first off you'll win an couple of HP's with taking the essembly off the motor and electric fans are just as good if in some cases not better...

i think an electric fans runs about 120 bucks orso, but i'm not sure bout that

 

[theofile]

Dear Jet Ski Puller,

I'm back from my trip to Lake George pulling about 4000lbs. Here's the results. We left on 6/14 with a full tank of gas and ambient temp of between 85 and 90. The truck worked wonderful for the 80+ miles. Stayed relatively cool and no bogging. Check engine light came on once briefly for a few seconds going down hill. On the way back, the truck worked fine for the first 2/3 of the trip, then I noticed some changes. Check engine light started to come on and the engine wasn't working just right. By the end of the trip, it was bogging. Yesterday, I asked a 75 year old friend of mine who's pretty mechanical, what he thought of the problem. His response - sounds like vapor lock to me. I think he's right. When we left for the lake, we had a full tank of gas. When the bogging began, it had a quarter tank left and probably a lot of vapor pressure. I'll be investigating how the Explorer system deals with vapor pressure. Have you made any progress with the problem?