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Discussion Starter · #21 ·
Well, again, you can look down the TB at the injectors and see how well they are firing. You could also add some fuel stabilizer/drygas to see if there is accumulated moisture in the fuel affecting it.
I watched both injectors last week when it was running well .... but thinking about that now guess it doesn't make sense to watch them when everything's good. Pattern looked good.

I added a bottle of red heet to about 1/4 tank last week, I think I'll take the fuel line off the tb tonight and run my fuel pump to see if anything clears outta the line.
 

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I don't see any mention of fuel filter. That has to be changed every 5 years or 50K miles. On my 92 Dakota, it's located on the top of the left frame rail, near the driver's door.
 
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Discussion Starter · #23 ·
I don't see any mention of fuel filter. That has to be changed every 5 years or 50K miles. On my 92 Dakota, it's located on the top of the left frame rail, near the driver's door.
Changed out the fuel filter this weekend and flushed gas through all lines from the tank. Fuel filter looked ancient and disintegrated as I removed it. Lots of yucky stuff dribbled out. While removing I tweaked the hard line that runs from the filter above the frame rail & it started spraying so I spliced in a hose up to the junction of hard line/hose as it runs down in front the of the engine. Pressure checked and all is good. Fuel had good flow into the TBI, couple blips on the electric fuel pump filled up the little spice jar I had stuck the hose into.

Started right up, perfect idle. Moved well under it's own power for about 45 seconds and then fell flat again. Sputtering, hesitating, tough to keep it running.

Watched the injectors more closely this time and noticed some dibbles and drops that land right on the throttle plate on passenger side. Driver side didn't look much better. It's gotta be gummed up injectors. I got a reman set coming tomorrow to try out. Only thing left after that is fuel pump pickup in the tank plugged up enough to kill pressure?
 

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I don't know if you should use regular fuel line or fuel line for fuel injected engines. I'd err on the side of caution and use the higher pressure fuel injection fuel line, but that's just me. I'm sure Walt or Bob L will know which is best.
 

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For fuel injection, use SAE rating 100R6 or 30R9 fuel injection hose, which is rated high enough. Return pressure is lower, but still, for safety and simplicity, use these ratings for both sides.
 
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You want to use the 'aircraft-style' clamps that won't cut into the rubber either.
If the fuel lines & brake lines are badly rusted, don't try just patching or splicing the leaking section, replace the lines for safety.


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Discussion Starter · #27 ·
I think I'm getting closer.

Got both new injectors installed tonight and it stayed running long enough to make a few observations:
-At IDLE both injectors were dumping fuel. I could see gas running off the throttle plates. I'm thinking similar to WOT levels of fuel.
-Most of the time it would start right up and then die
-The few times I was able to catch it running I watch both injectors and they were very erratic. At one point I was able to hold the rpms maybe ~2000 and I watched the injectors go from heavy spray to fine mist and the engine ran noticeably better until they started dumping again and then stalled out.
-Few times it looked like both injectors just totally quit and engine would die about 5 seconds later.

I'm pulling the following codes: 12, 14, 26, 33, 37.

26 is the most pertinent I think -- Peak injector current has not been reached. Which leads me to believe it is a wiring issue.
 

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Code 14 is a MAP sensor issue. A faulty electrical signal, either from a bad electrical connection or from the vacuum that generates it, could cause the fuel mixture to fluctuate. Check all ground connections if this hasn't been mentioned before, including the braided strap from firewall to engine.
 

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Back when i was chasing down what was ultimately my first failed ECM, when it was bucking and surging and farting, the map sensor code often came up, simply because the manifold vaccuum it was reading was well outside expectations, because it was burping farting and stuttering.

I've had a back up MAP sensor ever since, this June, it will be 17 years since I purchased it with such high hopes my burping farting and stuttering would disappear with its replacement.

The running fine, for X amount of time then stalling, often correlates to an overheating fuel pump. When yours stalls and does not want to run, when you turn the key on, can you even hear the fuel pump running for a few seconds?

My fuel pump got really loud before it failed.

The fuel pump strainer in the tank might be partially clogged, especially if the external fuel filter was so ugly looking.
 

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Discussion Starter · #30 ·
The running fine, for X amount of time then stalling, often correlates to an overheating fuel pump. When yours stalls and does not want to run, when you turn the key on, can you even hear the fuel pump running for a few seconds?
Previous owner installed an electric pump in tank so I flip the switch and can hear it before I even start cranking.

In the failure mode you're describing, with my pump ON I will crank for maybe a second or two and it catches right away and then dies roughly as soon as the key gets back to "run" I think it is only running for the duration of the injector start-up sequence which I've read on here is 8 pulses per crankshaft revolution versus the 4 pulses once in "run"

I estimate that occurs on maybe 9 out of 10 start attempts. The 1 of 10 it starts right up and just holds onto a normal idle OR I've given it the "sweet spot" amount of pedal and I'm able to hold onto a higher RPM, with occasional sputters, before it just quits.

I just keep coming back to the correlation of moving some wiring and harnesses around to get to my oil pressure sensor to replace it last month, and then essentially the next time I attempt a startup it acts like this....although like they say correlation is not causation. Going through the wiring tonight with fine tooth comb.
 

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Discussion Starter · #31 ·
MAP sensor.

Got it fired up and idling enough to stay running and kept giving a constant throttle and the injectors were just going nuts. From nothing to full blast. When I blipped the throttle it was like the injectors would over compensate in the other direction and there would be this weird back and forth oscillation.

Anyways, I knew MAP sensor was on my radar so I just unplugged it and immediately it began to run better. Smooth idle, good consistent throttle response. Drove it around the yard for 15 minutes to get some plowing done...no issues.

I have a new MAP that's supposed to come tomorrow, but is there any harm in not running one right now? From what I've read if MAP voltage is not present, the computer estimates fuel mix using TPS & RPM (Hall Effect).

Relevant codes now are 13 & 14. Makes sense.
 

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MAP sensor.

Got it fired up and idling enough to stay running and kept giving a constant throttle and the injectors were just going nuts. From nothing to full blast. When I blipped the throttle it was like the injectors would over compensate in the other direction and there would be this weird back and forth oscillation.

Anyways, I knew MAP sensor was on my radar so I just unplugged it and immediately it began to run better. Smooth idle, good consistent throttle response. Drove it around the yard for 15 minutes to get some plowing done...no issues.

I have a new MAP that's supposed to come tomorrow, but is there any harm in not running one right now? From what I've read if MAP voltage is not present, the computer estimates fuel mix using TPS & RPM (Hall Effect).

Relevant codes now are 13 & 14. Makes sense.
Correct, it will run a default table of fuel-air mixture with the MAP sensor unplugged.
When my MAP sensor failed once, it exhibited hard starting, rough running, stalling, loss of power, ragged performance. When it wouldn't start, I found I could hold the accelerator to the floor and turn the key, and then it would start fairly quickly, but I could not take my foot off the pedal without it stalling.
Sounds like you found the issue.
 
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