92 Dodge W250, Trouble tracking down a miss

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92 Dodge W250, Trouble tracking down a miss

Postby matthewh » Wed Jan 27, 2016 2:04 pm

Same truck as was discussed in the BS thread about injectors. A list of what's been dons so far, new plugs, distributor, oil pump.intermediate gear and bushing, tps sensor, fuel filter, one new injector, reman'd ECM, and redid the positive and negative wires at the battery to std lugs and a new 31 series battery with threaded posts.
It had a bad miss under load, and I found one injector dead. Replaced it when I did the ECM yesterday and threw 5 gal of fresh gas and a can of sea foam in the tank, since the gas smelled old, and the trucks been sitting at my house since October, and idk when the po filled it last.
Ran beautifully today while plowing, tons of power, you could floor it and it'd just go. Most the drive was done, coming off a bank in reverse, and the miss came back. Half-3/4 throttle in 4lo, can make it miss almost every time. Sometimes in forward, but mainly in reverse. Fuel.gauge shows just over 1/4 tank.
So, chance its bad gas/water, or a draw straw issue? I've heard of guys having issues with low fuel levels and a miss due to this. Has good fuel psi, 32lbs at idle, which is factory spec. It feels like a fuel miss, not a spark miss, but at this point in lost,

Thinking back, I noticed when idling outside my garage while I cleaned the snow off, it high idled a couple times for a second, but iirc that's a dirty iac motor. Idk if that would have an issue any other time.

Thanks
'93 W350 5spd Getrag, 4.10 gears, 83k miles and counting, Mods: LPPP AKA Ma Dually
'54 Dodge M37 6.2/700R4/205, 5.89 gears, WC rear axle
matthewh
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Re: 92 Dodge W250, Trouble tracking down a miss

Postby PToombs » Wed Jan 27, 2016 6:08 pm

Not that I have a lot of experience with gassers, here's something I learned. I had a 95 with a 318, it had a real bad flat spot off idle. In my fruitless search for it I pulled rails off the injectors and there was rust on the injector screens. I flushed the rails and they were full of crap, I don't think I ever got them cleaned out. There wasn't really a fuel filter on it, it was more like a strainer. I was surprised how much rust was that far up the fuel system. Turns out the flat spot was caused by a vacuum leak someplace, I never found it, just plugged that line off.
It's possible that you have another bad injector, you may have crap in the fuel rails or migrating around in the system.
Maybe have somebody put it in gear and load the engine while you carefully (safely?) pull injector wires to find the bad one.
pete

Just enough power to break everything behind the crankshaft.
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PToombs
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Re: 92 Dodge W250, Trouble tracking down a miss

Postby matthewh » Mon Feb 01, 2016 5:56 pm

Spent some time on it this weekend. Swapped the coil out with a new one, as well as a new set of plug wires, because j noticed with the shop dark, at higher rpm's the coil wire would glow where it crossed the valve cover. To insure a good ground at the coil, I ran a ground wire to the core support from the mounting bracket.
Still runs like sthi. Anything off idle it misses and bucks, backfires etc. I had noticed the coolant gauge wasn't working, so I shut the truck off and fiddled with the connection, and while the gauge worked again, and the truck ran better, it still missed at times and a noticeable backfire out the pipe when rpms return to idle. Also noticed a pronounced "chuff" from the exhaust as well, but the Mrs says it's always been there, it was warm, had the windows down today, so its possible I never noticed

Other than fuel level related, as the gauge shows almost empty, I'm lost, and ready to send it to the yard. I have no clue what's going on, no codes to follow, and I believe I've replaced almost everything ignition related. I may throw 10-15 gals of gas at it and see what happens, it needs GA anyways to keep plowing, even if it runs like sthi
'93 W350 5spd Getrag, 4.10 gears, 83k miles and counting, Mods: LPPP AKA Ma Dually
'54 Dodge M37 6.2/700R4/205, 5.89 gears, WC rear axle
matthewh
14mm rotor
 
Posts: 633
Joined: Mon Feb 18, 2013 3:07 am
Location: Boyne City Michigan
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