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1994 Caravan 3.3, starts and dies

5K views 12 replies 6 participants last post by  edmost 
#1 ·
Hi Everyone, new to the site. I've got a problem with my Grand Caravan. I just received it from the previous owners who gave up on attempting to find it's problem. Here's the specifics 1994, 3.3, 150,000, with fresh
plugs, wires, coil pack runs on an Intrepid, crank sensor is still
magnetic and cleaned (but I don't know how to check it correctly), compression is 150 across the board, fuel
pressure is 50 cranking and running (if you can call it running), air
filter is new. Now the bad. Van cranks and fires right up, but
immediately dies (within a second or 2). If you pump the accelerator
it'll keep running for awhile, cycling up and down as you pump. Smells
flooded and dies as soon as you let off or if you hold it to the floor
or you get out of rhythm. I pulled up the rail with injectors still on
it and none of them leak and all seem to be firing as they should (to
the naked untrained eye) when you crank it over. There are no codes.
Everything else seems to be operating normally, all fuses and relays
are good. I'm hoping to try a new camshaft sensor tomorrow, and
hopefully find an engine computer at the bone yard. If neither of those
is the fix, I'm at a loss. The only other thing I could think of is the
timing chain slipping, but I figured it'd still run, just poorly or the
compression would be down. Anyone have any ideas or know how to check
the timing chain w/o disassembling the entire front of the engine? On a side note, the second it runs by itself it sounds perfectly fine.
Thank you very much for reading.
 
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#2 ·
I was going to suggest checking for vacuum leaks but that would require keeping the engine going long enough to get a meaningful reading. Will it run at higher rpms, say 2000?
At 150,000 miles, you would almost certainly be ready for a new O2 sensor if the previous owner hadn't replaced it. Another possibility would be exhaust related if the converter has plugged up and is creating back pressure.
 
#3 ·
I can't keep it going at any steady rpms because it just dies. It'll only idle for a second or if I keep revving it at a specific rhythm it'll rev up to 2000 or so in cycles and right back down. If I hold it on the floor it dies in a second. I never thought about the cat being clogged, maybe i'll try disconnecting the exhaust or have someone hold their hand over the pipe next time I get it running. The odd thing is that it always starts right up, then shuts right off. I'll try the exhaust check. That's the one area I never considered. It's nice to have a second opinion.
 
#4 ·
That cat seems like a good thing to check. Does it have a map or maf on this year? Most of the sensors can be checked via a ohm/volt meter. What does the oil smell like? If it smells of fuel then it might be that the fuel pressure valve is stuck open and flooding too much fuel into the cylinders.
 
#5 ·
Update time-
Tonight I disconnected the exhaust at the head pipe (just before the cat), no change. Tried 2 different junkyard cam sensors, no change. The van has a MAP sensor, didn't read your post before I went to the yard or I would've grabbed one or 2 of those also. I also picked up a PCM (engine computer) today at the yard, going to try that in the morning. If it solves my problem, I'll post back immediately, otherwise I'm going to drown my sorrows in a case of beer or 2 up north over the weekend. I thought if the MAP was bad, the car wouldn't start, either way, I'm going give her a couple of taps after I find out that the computer change didn't solve the problem. Thanks again for the replies.
BTW, oil's free of gas and I took out the fuel pressure regulator tonight (it's new) just to make sure it was installed correctly.
 
#7 ·
Not too close to tulsa, SE Minnesota. I'm about ready to run it off a cliff though. Anyway, swapped out the engine computer for the one I got at the yard, no change. I banged on the map sensor for awhile, no change. Tomorrow I'm going to stop at the yard again and get a crank sensor and a map sensor. Otherwise I'm completely lost.
 
#12 ·
Yes it does. It's located in the middle of the engine (side to sidewise that is) and screws into the back (firewall side) of the upper intake plenum. That MAP sensor fits 90 - 95 Caravans/Voyagers/etc with a 3.3 (some 94&95s with 3.8) and also 93-97 Intrepids/etc. with a 3.5.
 
#13 ·
Thanks for the above info. I suspected the MAP sensor but found that wasn't the problem.

This is 1990 3.3 L Caravan w/ 130,000 miles so understandbly its had its share of work done on it. What we found is a wire that was rubbed raw from presumbly the serpentine belt or one of the pullies. It is connected to the Crankshaft reference sensor, I think. It was causing intermittent voltage shorting and thus lieing to the system. Its just a thin yellow wire (down by the serpentine belt). My man by-passed it with a loop of wire connected to a couple of alligator clips and V-ROOM! A splice of the wire to make a permant fix and the vehicle is starting and running.

It was hard to see (this raw wire) and I think the Dodge gods must have been on are side. This time. Just some backyard guys trying to keep 4 wheels on the ground. Good luck to all with this sort of problems...
 
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