Intermittent Sputtering/Stalling

[Too old to Care]

This one is driving me crazy; I need ideas:

1985 CJ7 , AMC 258 i6 / 4.2l , Howell EFI, stock distributer. Daily driver. Remanufactured engine was installed in 2004 and Howell EFI conversion at the same time. I do all my own work and the CJ ran flawlessly for 8 years from day one until a few months ago.

Symptoms: After a few miles the engine will start to sputter and try to die. I have to pull over and pump the throttle vigorously for 4-8 minutes to keep it from dying. Then it will suddenly run fine, but will do it again within a mile or two. I cannot determine a common situation or factor; sometimes I can drive it a week without incident, sometimes only a few days, sometimes it does it every day. Sometimes I get an ALDL code 44 & 45, sometimes no error codes at all. Always starts fine when not driven for a few hours.

Actions to date: Changed rotor & cap; checked hoses and wires for breaks, shorts & loose connections; replaced fuel pump & filter; replaced fuel regulator in throttle body; replaced fuel injectors; replaced fuel pump relay; new hard fuel line from pump to TB; replaced ignition control module.

What have I missed??? If the ECM is bad it should kick out an ALDL code shouldn't it? Do I need to drop the fuel tank and look there?

I know a lot, but I don't know everything. Any of you motorheads run across this before? Thanks.

 

[Old Dog]

It seems like you changed everything I was thinking of as I read this.
The only other thing I can think of is to drop the tank and change the sock filter.

 

[Torxhead]

You can call Howell Engine Developments, their customer service has a great reputation. I see you have replaced the fuel pump and icm, but make sure that they do not get warm to the touch, as that will indicate where the problem is.

 

[Too old to Care]

Ya, I shot Howell Inc. an email describing the situation. Haven't gotten a reply yet.

Another random thought: 20gal gas tank. I haven't dropped the gas tank since about '96. How is it vented? , Is it possible a roll-over valve is sticking closed and creating an intermittent vacuum issue in the tank?

 

[Torxhead]

Howell is very poor on e-mail responses, I should have mentioned that, you have to call them on eastern time. I believe there are two roll over valves in the large tank. Gas tank vent system can be tested by removing the gas cap after a drive and listening for air rushing in. Most Jeep repair manuals have a vent system printed out inside. A vacumn will form in the tank as gas is used if there is a bad vent system. A lot of can collect in a tank after 25+ years. I would like to know how you got a NV3550 in that CJ.

 

[Too old to Care]

Thanks Torxhead. Looks like I'm going to pull the tank.

Sorry for going off topic:
I bought the NV3550 for $400 from a guy doing his own build on a 2001 TJ. Came with the bellhousing & cover plate. I had already converted to a hydraulic clutch set-up so I only needed a compatable slave cylinder. For various reasons I didn't want to reclock the Dana 300 Transfer Case or drill new mount holes, and instead went with an adapter kit.

The biggest headache was the dang pilot bearing; No-way, no-how could I find one the right size. I got one that was close but had to make my own shims from brass straps to keep it pressed in the crank. I later pulled the tranny back because of a cheap P.O.S. throw-out bearing failure, so I took that opportunity to have a bronze pilot bushing made to fit. If I ever pull the engine again I'll probably have the end of the crank milled for the right size bearing.

Had the rear driveline shortened and the front lengthened and shimmed the back axle to correct angle. Front was close enough. (I think the back was wrong anyway).

Suprisingly the stock Transfer Case shifter bolted up, but it was a puzzle. I heated both shift levers and re-bent to position properly and made a new floor pan since the NV3550 sat rearward about 1 1/2" from stock.

It was a little work, but with planning it came together nicely. Before that I went through (3) T-5 's because I was always getting conflicting info on what gear oil to use....I'm lovin this NV3550.

 

[hole]

I had a similar problem with my 8 years ago. Ended up being a pinhole in a short section of the factory steel line between the pump and tank, causing air lock on the electric pump. Hope you find what's causing your problem, nothing worse than wondering when and where you'll get stranded next.

 

[Too old to Care]

Thanks hole, I think you might be onto something. I haven't touched anything behind the fuel pump since replacing the sending unit about 15 years ago.

For any of you diagnostic guru's still following this thread, I may have found a common denominator:

I drove it to work and back 4 days this week without incident; thats about 3 miles one way thru town, stop & go with hills. Although it cuts out as described at random times & distances, 99% of the time it will sputter and stall on one particular road at almost the exact same place. It's after driving about 7 miles on flat road with a steady throttle at a constant 35mph. Almost like a switch it sputters out, I pull over fight & swear at it for several minutes, then it clears up and runs fine.

Any clues?
(besides the wise-cracker that will undoubtedly post: Well then, don't drive on that road!)

 

[Torxhead]

If you suspect it might be a fuel delivery issue, a visual inspection might reveal something. Like any kinks or leaking fuel from the lines. The line from the fuel tank to the pump works pretty much like a siphon to deliver the gas to the pump, any leaks will upset that. The system does work best on a full tank of gas. Another way to check fuel delivery will be with a fuel pressure gauge, in your case an electric unit located in the cab so you can compare fuel pressure with engine operation. Howell recommends 10-12 p.s.i.

 

[hole]

The only time my pin hole leaked was the day we found it. A buddy of mine wrapped a shop rag around the end of an air nozzle and gently blew air through the filler neck while I crawled around looking/listening for a problem. Within 20 seconds the small drip started. It was a small section of factory line, leftover after the Mopar MPI was installed, that had rubbed a small pinhole from rubbing on the bed.