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Unread 08-30-2014, 05:55 PM   #1
91HunterGreen
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Howell EFI Problems !

First posting. I recently purchased a '91 Grand Wagoneer and had some issues this morning. The vehicle started fine and I drove it about 4 miles and then started up a steep hill and had very little power. The vehicle would not increase in RPM and I crawled up the hill at 5 MPH tops. The engine would not increase in RPM no matter how much accelerator I applied. Got to the top and pulled over in a flat parking lot. Popped the hood, engine ran fine at idle, got in the vehicle and hit the gas and the motor RPM increased fine. Put vehicle in drive and no power, RPM's would not increase.

I am assuming something is wrong with the Howell EFI that came with the vehicle ? Or is it a fuel delivery issue? Fuel pump? Blocked fuel filter?

Any thoughts would be most helpful...

Thanks

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Unread 08-30-2014, 11:29 PM   #2
super98lsc
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If it were fuel pressure it would likely lean pop etc. does it sound odd like it's sucking air when you are trying to accelerate??
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Unread 08-31-2014, 05:50 AM   #3
91HunterGreen
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No Power up Hill

The more I think of it I drove over a bumpy railroad track first at the bottom of the hill then started up and had no power, I mean 2MPH up the hill. I think the catalytic converter collapsed and I have a blocked exhaust. That would explain the odor near the top of the hill. First I'm going to do though is change the fuel filter and put fresh gas in the Jeep. Who knows how long the gas has been in this vehicle. Next I am going to start the vehicle and have someone press the accelerator and I'll feel the flow out of the tailpipe. If the fuel filter change does not do it, then my first attempt will be a muffler shop to test the flow of the exhaust system. If that's not it then it's off to the Jeep dealer and they can figure it out.
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Unread 08-31-2014, 08:23 PM   #4
gpcl16
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That would have to have been one hell of a bump to destroy your cat, I guess it's possible though. If your cat was destroyed you would probably hear pieces of it rattling in the exhaust when you revved the engine. A good, non-invasive check for clogged exhaust is to hook up a vacuum gauge to your manifold. Hold the engine steady at about 2,500 RPMs and watch the gauge. You should see steady vacuum of 19-23." Hold it there for a minute or so. If it slowly starts to drop then you likely have a restricted exhaust. If it stays steady then that's probably not your problem. I would also check all of your wiring and see if something came loose when you hit the bump. Especially the problematic plastic horseshoe connector to the ignition coil and the big wire from coil to the distributor cap. Also check that your distributor is tight and can't be turned by hand.

It sounds like possible vapor lock??? Though I would think that if there was a lack of fuel you would probably be getting lean pops, stalling etc. when you tried to accelerate (like super 88 mentioned).

IMO I wouldn't bother taking your GW to a Jeep dealer. They'll have no idea how to work on it there. They might even turn you away. Take it to a shop that specializes in vintage cars. Virtually everything on your car is early 70s technology with the exception of your Chevy style Fuel Injection setup, which the Jeep dealer will have no idea of how to troubleshoot.
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Unread 09-01-2014, 06:43 AM   #5
super98lsc
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Blocked exhaust would explain this for certain. If the cat got hammered hard enough only takes one chunk of that internal honeycomb to get turned sideways at the inlet or outlet and bam done no flow.
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===================================
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Unread 09-01-2014, 10:46 AM   #6
CSP
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Being 23 years old makes it entirely a possibility that the cat could be coming apart inside.
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Unread 09-01-2014, 11:58 AM   #7
gpcl16
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Okay I guess the busted cat is a good possibility. The test I mentioned with the vacuum gauge works really well.
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Unread 09-02-2014, 05:40 PM   #8
91HunterGreen
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Tune Up

I checked the heat riser first and the spring is tired, so I wire it open to avoid any exhaust blockage issue. Poured 10 gallons of premium gas in to mix with the 10 gallons in the tank. Thought I'd better rule out tune up issues first and pulled the distributor cap and was amazed at the corrosion at all eight points. It looked like bad corrosion at a battery terminal. All fuzzy and no visible sign of metal that the equally as ugly rotor could make contact with. Bought a new cap, rotor, wires, and spark plugs. I pulled one plug earlier and it looked pretty good, but I wanted to start with a tune that I know is all new.

Next step is to start it and see how it acts. I am still thinking its the catalytic converter that shut down the power. Same thing happen at the same RR tracks before the hill to friend. If its an exhaust blockage issue I will delete the Cat in its entirety since Ohio stops checking for emissions on vehicles that are 25 years and older and I will not have to check again until after it reaches 25.

If that's not it then it could be the big fuel filter that is located at the frame rail as part of the conversion to the Howell EFI kit. If that's not it then the Howell somehow is messed up.

Attached photo of the '91, hope the up load works as this is my first attempt.
It has 69K miles and lived most of it's life in Nashville.

Thanks, I'll keep you all posted.
imagejpg1.jpg  
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Unread 09-02-2014, 09:57 PM   #9
CSP
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You sure jump to the conclusion that the EFI is messed up quickly. You could have a vacuum problem, it could be a blockage in the gas tank, it could be an ignition issue, etc. The idea is to troubleshoot, not jump to conclusions.


There is no exhaust that passes through the heat riser. It's air in the engine compartment and it just allows that air that's surrounding the exhaust manifold (and warmer than the surrounding air) to pass into the air filter housing when the temp is below a set temp.
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Unread 09-03-2014, 10:11 AM   #10
GCX2450
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According to your first post, the issue is only present when the truck's in gear. Did you check to see what it would do in Reverse, Neutral, 2nd and Low?
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Unread 09-03-2014, 06:08 PM   #11
91HunterGreen
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Csp

I am systematically eliminating the possible issues as I proceed. Time will tell if it leads me to the EFI. Don't discount that the EFI may not be the issue. My original posting subject title should of had a ? instead of !, other than that my follow up posts have been about all other components besides the EFI.

My money is on the Cat as the issue, but not there yet.
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Unread 09-03-2014, 06:17 PM   #12
91HunterGreen
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Gcx2450

No issue with the transmission, works fine in all gears. The Jeep just doesn't have the power to spin up the RPMs. Engine will not rev up under any load such as driving on flat ground. The increase flow of the exhaust when the engine is working bogs the Jeep and eliminates almost all power. At idle it will rev up but not at a normal rate, under load it dies.

I think it's the Cat or even the muffler that is soft to the touch which will lead to a straight pipe and new muffler. This vehicle sat for 7 years in a dry garage being pampered and was only driven 200-300 miles over that time. That's not good for an exhaust system that doesn't go through heat cycles.

We'll see.....

Thanks for the posting.
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Unread 09-03-2014, 08:53 PM   #13
CSP
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Quote:
Originally Posted by 91HunterGreen View Post
I am systematically eliminating the possible issues as I proceed.
Sorry but going from clogged exhaust to fuel filter to EFI is not systematically eliminating anything. They may be what you consider the logical steps, but there are plenty between the fuel filter and EFI that you aren't considering.

I'm not saying that it can't be the EFI, but chances are if it's not throwing a code, that's not the source of the problem. It's based on GM TBI and pretty bulletproof.
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Unread 09-07-2014, 08:09 AM   #14
super98lsc
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X2 on what CSP said. Also running it any more if that cat is blocked will destroy valves and other things. Just drop the pipes off the manifolds. Run it without exhaust prove it out then after new exhaust is installed do the tune up.
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06-Corvette z51-6spd,b&b,K&N low miles.
77-Corvette Stingray 496 BBC/TH400 built 667hp+
===================================
00 WJ 4x4, 4.7 stroker, turbocharged,..lots more..
01 WJ 4x2 4.7v8 Limited (needs valve job)
90 Grand Wagoneer 401 Edelbrock Heads, Lunati .510/.527 FT Cam, Edelbrock RPM Air Gap, Holley HP 750, Thorley Headers, HEI, Electric Fan w Digital controller,4" lift 31x10.50 Goodyear Duratrac's on Pro-Comp Wheels,new interior, seats,seals,Alpine and JL full system, Remote HEI, Clifford 2 way with remote start,windows,tailgate.
96 Cherokee Country 4dr/2x2 White/Tan 3" Lift Sahara 18" Wheels 32.5"'s 99up head and intake- for sale soon!
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