Forums
Forum Tools
|
 |
23:54:53 - 12/19/2024
V6 Dakotas
| From | Message |
Jim
Dodge Dakota
JOIN HERE
5/26/2015
13:30:47
|
 Subject: 1989 3.9 Intermittent Start Expert Help
IP: Logged
Message:
1989 3.9 Intermittent Start Expert Help Needed Please?
Hi,
I'm new to this forum but not to troubleshooting. I need facts to help fix the problem I'm having with this 1989 Dakota SE 2x2 3.9l SWMBO just picked.
Background: After sitting for most of a decade with ~1/8 tank of fuel, the PO sold the truck to She Who Must Be Obeyed. It was well cared-for for its 103k miles but sat in the sun neglected for most of a decade until we got it.
After jump-charging the "new battery" (1.1v initially), it cranked, started & ran well enough to show us the split heater hose. Shut it down & let it cool to repair that.
After agreeing to buy the truck, airing up the tires (0psi each) and jump-charging the battery again, it "caught" after a few tries & ran well enough to impress me (not easy to do), charge the battery and get me to the dump to empty the bed, then to get a fresh 1/2 tank of gas. Seriously impressed with this, our 2nd Dakota!
Then after concluding the purchase, it cranked well & started after several tries (expected with old, bad gas) and got us home on the dry-rotted, flat-spotted old tires. Going to replace the tires, it fired right up to g-g-g-get us th-th-th-there (shaking on flat spots :) as you'd expect) but took 10+ tries to get it started to get out of the tire-store bay.
The problem: Cranks well but usually refuses to start until after many tries or use of Starter Fluid. When it does start, it runs exceptionally well.
Assuming bad gas, we've run Seafoam and B12 Chemtool through it constantly (~500mi so far) to clean the fuel system. While cranking (for good or bad) you can definitely smell the typical "bad gas" stank in the air, but when it's running the exhaust smells clean.
The battery/charging/electrical system is fine.
When it does "catch", it runs amazingly well, pulls strong from a stop, shifts neatly and holds freeway speeds w/o much pedal. The pedal response is flat through the middle 3rd of the range, & doesn't matter where I hold the pedal. The cleaning fluid seems to be improving that throttle response, gradually.
The thing is, we can never tell when it will fire right up, or refuse to start.
When I look into the Throttle Body while SWMBO cranks it, I can see gas spraying strangely:
When it's running, we get nice, fine cones of lots of gas, constantly (no pulsing I can see w/ LED flashlight)
When it is in its failure mode, while cranking, the gas still sprays; but it's "blobby" and weak-looking until it "catches".
Once or twice, it has cut off when approaching a stop, but fired right back up in Neutral w/o impeding any traffic.
It sometimes fails to start when cold, but sometimes fires right up when cold. Sometimes it fails to start after being shut off for a few minutes w/o a lot of trying or Starter Fluid, but sometimes it fires right up. Most of the time, restarting after, say, a store run, it will start, but not every time. Starter fluid gets it going every time, but even then it sometimes takes a couple of tries.
We can't actually predict when the hard-to-start problem will happen.
My belief is that there's a different signal going to the injectors or fuel pump during cranking, than when running; judging by the different spray patterns in the TB. I can't "make it fail" so we never know if we'll be driving right off or sitting patiently awhile or risking a broken motor from the Starter Fluid.
Starting procedure: Turn the key to Run until the throttle override motor moves the pedal a little (~1sec) then try to crank for no more than 2sec. When it fails, power OFF until that motor puts the pedal back (~1sec - you can hear it moving) then back to Run until the pedal moves then on to Start. SWMBO claims that a >5sec crank sometimes works, but that has not been my experience & I don't think that's wise.
Once or twice I've tried holding the pedal to the floor for a couple seconds of cranking in case it's flooded, but that doesn't help at all.
Please pardon the wall of words, but I'm just stumped! I admit I'm no "Dodge Boy", and not all that familiar with TB fuel injection, but I hope I've given some expert enough information to help clue me in to what might cause this uber-weird problem.
Can anyone offer a suggestion as to what might be going on here? We really love this truck, even with the problem, but it is driving us nuts trying to get it to start reliably!
THANK YOU for reading this far, and for any help you care to offer! I joined this forum to post this, in hopes the answer (which I WILL post when I know it) will help someone else someday.
PS: We replaced the Steering Rack (open leaky seal) and the totally-perished plastic bushings in the Wiper Transmission so I'd be glad to write up those procedures or help anyone having trouble with them...
Thanks again,
Jim
|
Derek M. Coll
Dodge Dakota
JOIN HERE
6/04/2015
09:17:33
| RE: 1989 3.9 Intermittent Start Expert Help
IP: Logged
Message:
So i as well was having this problem after
looking deeper into this i found i had a holly 4
barrel carb. and come to find out the fuel pump
was not strong enough to support the truck
starting. so after replacing the fuel pump and
filter, it starts with little or no trouble.
another issue is make sure your seals and
diaphragm on the intake isn't broken.
|
| | P 1 |
|
Post a reply to this message:
Username Registration: Optional
All visitors are allowed to post messages
|
|
