Well, as always, it's been a learning experience.
Emergency - Can a mechanical fuel pump fail intermittently?
Hey guys,
My '87 3.9L Dakota just quit on me and I've got to get it fixed TODAY. I think it's the fuel pump, but let me know if you think it's something else.
Going down the road the engine just died - no sputtering or anything. BUT when I pumped the gas it ran briefly, less than a second. That was while I was still coasting in Drive. It did that the first 2 or 3 times I pumped the gas, but not again.
After sitting about 45 minutes, it started after cranking for a couple of seconds.
I think the carb is being starved of fuel, the brief seconds it ran were when the accelerator pump shot fuel from the bowl (assuming this carb has a bowl), but then ran the bowl dry. I think that's also why, when it did start again, it took a few seconds of cranking.
But I don't understand why it would start again after sitting a few minutes. That's what makes me unsure if its the fuel pump or not.
The fuel filter was replaced in August.
If I was flush with cash I'd just slap a new pump and filter on it. Right now I've got be careful what I spend the $$ on.
I thought about water in the gas, but wouldn't that make it sputter for a while before it just quit completely?
My '87 3.9L Dakota just quit on me and I've got to get it fixed TODAY. I think it's the fuel pump, but let me know if you think it's something else.
Going down the road the engine just died - no sputtering or anything. BUT when I pumped the gas it ran briefly, less than a second. That was while I was still coasting in Drive. It did that the first 2 or 3 times I pumped the gas, but not again.
After sitting about 45 minutes, it started after cranking for a couple of seconds.
I think the carb is being starved of fuel, the brief seconds it ran were when the accelerator pump shot fuel from the bowl (assuming this carb has a bowl), but then ran the bowl dry. I think that's also why, when it did start again, it took a few seconds of cranking.
But I don't understand why it would start again after sitting a few minutes. That's what makes me unsure if its the fuel pump or not.
The fuel filter was replaced in August.
If I was flush with cash I'd just slap a new pump and filter on it. Right now I've got be careful what I spend the $$ on.
I thought about water in the gas, but wouldn't that make it sputter for a while before it just quit completely?
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It's a bummer to spend money that you'd rather not on an old vehicle, but it really will run a little better than a straight pipe with a new catcon. Anyway, hope you find out what caused it to run rich in the first place. It really could be just its age that caused the failure. But check the EGR transducer to see if hot exhaust backing up caused it to melt - that happened to my brother when he owned my Dakota.
The only option right now is the least expensive patch to get it to run further than a few miles. I'll decide at a later time whether to replace the cat. The Dakota has been an excellent vehicle until now despite its age and cosmetic issues. I don't mind spending the money on it, when I have the money. Being out of work for 3 months tends to put a dent in one's budget.
Where the air injection tube goes into the cat, is that a screw-in fitting or what? Wondering what I'm going to need to remove it.
Mine had a hex nut, but I don't think it can ever be unscrewed, it will be welded from the heat. When mine rusted out there, I had it welded, and when it rusted again, I bought a new catcon that came with the pipe and a silicon hose to clamp between it and the air injection tube. But I found that the metal tube at the catcon came with a cap to cut off and attach the hose, and I left it capped. I did without the air injection tube, and in the two following emissions inspections, it passed and gave exactly the same emissions readings as all of the previous tests since new, without the tube. The catcon seems to function the same without it hooked up. It relies on suction to draw the air down from the air cleaner, but it seems it wasn't really effective. The catcon did all the work.
Now wait a minute - isn't that tampering w/ the emissions system? 
If the air injection doesn't make any difference, I'll just cut it off at the converter and tie it back.
If the air injection doesn't make any difference, I'll just cut it off at the converter and tie it back.
If I could restore it, I would, just to put it back the way it was. But the air injection pipe rotted out, and it's unavailable. No Mopars older than 2000 in any junkyards around here.
The air injection pump on my Dakota is frozen, so leaving the tube disconnected won't make a difference anyway. I saw one online for $35. I'm lucky that I found a Dakota in a local pull-a-part that is the same year, engine, and paint scheme, so I may try that before buying a new one. After I figure out how to get the dang exhaust manifold off the one at the pull-a-part (the left manifold on mine is cracked - one reason why I haven't replaced the O2 sensor yet).
Had the catcon removed and a straight pipe welded in. You could barely see any light through the catcon. The salvage on the old cat more than covered the cost of having someone weld a pipe in instead of trying to clamp one in myself. I have not had any hiccups from the engine since then.
As soon as possible I'll replace the O2 sensor along w/ the left manifold, and then do a rebuild on the carb.
As soon as possible I'll replace the O2 sensor along w/ the left manifold, and then do a rebuild on the carb.
Bob, is that the '92 Dakota listed in your sig? There's several Dakota's at the pull-a-part here... I was only looking for '87, but I can check for a '92 next time I'm there.Bob Lincoln said:If I could restore it, I would, just to put it back the way it was. But the air injection pipe rotted out, and it's unavailable. No Mopars older than 2000 in any junkyards around here.
No, there was never any air injection on my Dakota. Both my 92 and my 93 Daytonas had air injection.
Still having minor hiccups once the engine warms up. Feels like the engine cuts out for a split second. It doesn't happen until the engine is warmed up, and becomes very pronounced when I accelerate. It doesn't keep me from accelerating, though. Could this be caused by the distributor pickup that was mentioned earlier?
Glad you have most of the issues resolved.. I usually just slice the pipe behind the cat.. Clean it out.. and put a splice over the cut.. Or the single weld would be an inexpensive fix from there too.. and with the Converter body under it. it can still take an emission test if necessary. The computer and sensors will keep the emissions low enough to pass with the converter empty.. I've passed 3 cars with that failed by doing no more than cleaning out a bad cat and retaking the test.
I'd be more suspicious of the carb or O2 sensor for the cut out. It could be ignition related but sounds more like fuel.
Any fault codes at this point?av8r115 said:Still having minor hiccups once the engine warms up. Feels like the engine cuts out for a split second. It doesn't happen until the engine is warmed up, and becomes very pronounced when I accelerate. It doesn't keep me from accelerating, though. Could this be caused by the distributor pickup that was mentioned earlier?
Could be many things - burned dist/rotor contacts, dist pickup, bad TPS or its wiring, bad ground connection. I'd do more diagnostics before buying parts.
After I posted I realized I need to check basics like plugs, rotor, distributor, timing, etc.
There won't be any fault codes on the 1987 Dakota - it requires old fashioned diagnostics like pulling the plugs and analyzing the appearance.Any fault codes at this point?
The stuttering/hiccupping happens only on the highway - once in a while at a constant speed, then more often and pronounced if I go up a hill and have to open the throttle more. It does not stutter at all when pulling away from a stop light or when driving street speeds like 35 - 45 mph.
I want to check the timing, but I don't have a tachometer. How vital is the tach to getting the timing set correctly?
It is important. You need to be at the specified idle so the distributor isn't advancing the timing due to the RPMs.
Checked the timing w/ the RPM around 700, the idle contact button grounded, and the vacuum hose to the Spark Control Computer capped. The air pump isn't belted, so didn't bother disconnecting the air switching valve.
Found the timing was advanced about 15 degrees (it was above the 10 degree mark by about half the distance between 0 and 10). The decal says set it to 7 degrees BTDC, so I put it a little above halfway between 0 and 10. Had to do it twice because it would advance 4-5 degrees when I tightened the hold-down bolt.
Based on a 10 minute drive on the highway, this seems to have fixed the stuttering problem. Nice! I'll take a longer drive next Sunday and find out for sure. Hopefully this will also help w/ the running rich and the MPG.
Found the timing was advanced about 15 degrees (it was above the 10 degree mark by about half the distance between 0 and 10). The decal says set it to 7 degrees BTDC, so I put it a little above halfway between 0 and 10. Had to do it twice because it would advance 4-5 degrees when I tightened the hold-down bolt.
Based on a 10 minute drive on the highway, this seems to have fixed the stuttering problem. Nice! I'll take a longer drive next Sunday and find out for sure. Hopefully this will also help w/ the running rich and the MPG.
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