Problem Quitting While Driving

My 92 transport 3.1L had started quitting on me while driving. After sitting for about 15mins I could get it started and then continue on driving. Now its doing it more and I can't take the chance of going anywhere in it.

Help me out please! got a CEL so I flashed codes 34, and 45. Any suggestion on where to start troubleshooting with what these codes are saying that I should do? Thanks

Does this have a distributor?

34 is the Map sensor

45 is the O2 sensor(running rich).....

When the car won't start, do you have spark?

What is the fuel pressure when it won't start?

Yes it has a distributor. It along with the rotor and module were replaced awhile back. There is spark during the crank. As for the fuel pressure I really don't know. Never had a way to test when its quit on me.

WIth TBI, you can pour some fuel into it after removing the air filter....if it starts this would prove the problem with fuel supply...
Fuel pressure with TBI is merely 10-12 psi....but then the fuel pump must run. Can you hear it run ?
http://www.avigex.ca/xport/fuelpumptest31.jpg
http://www.avigex.ca/xport/31fuelcontrol.jpg

keep this for codes
http://www.avigex.ca/xport/codes31.jpg

Is there any fuel coming out of the injectors in the throttle body when it won't start?

As of now it runs but I don't take the chance driving it. I sometime this week will get someone to follow me and hopefully it will quit. I will then check the fuel supply. Question- How would lack of fuel cause a running rich. Anyway I will get back with some observations. Thanks guys

Question- How would lack of fuel cause a running rich.
I would just see it the opposite. A false rich reading might cause leaning of fuel injection to the point where it cannot ignite.....but this is probably an extreme condition......where the O2 sensor would be way off calibration...

Anyway...."closed loop operation"...that is when the computer really takes O2 reading in consideration....applies only once engine has warmed up......to 145°F I think...which would explain why it (the problem) happens only after a few minutes.....otherwise it runs on "default" parameters. One way to test this hypothesis would be to fool the temperature sensor....like by simply disconnecting it. Once disconnected, it reads infinite "ohms" resistance.....corresponding to very low temperature. This would inhibit "closed loop" operation.....then test what happens then...... of course it would pop a "low temp" code.....but ignore that and run for a test.....and report.....

I have not been able to spend any time trying to solve problem. I am in and out of town as of late. Getting ready to leave again this morning. Hopefully I can try to test in a few days if cold weather holds off. Will keep you posted. Thanks

I let the vehicle run for about 20 mins and then turned it off and disconnected the temp sensor. When I tried to start it (sensor disconnected still), it just cranked however I could smell gas.

After leaving it sat for awhile and than connecting sensor back, it if finally started. I let it run for a good while then disconnected the sensor while running. The only change was that the fan kicked on immediately and continued to run, the vehicle never died.

Finally shut the engine off and tried my first beginning test above, and it started. No cranking. Any ideas what all this means? :jerking:

..then disconnected the sensor while running. The only change was that the fan kicked on immediately.. :
..ok..it probably detected a failed temp sensor and to be "fail safe" it kicked the fans ON. ANd....this must have come with a DTC15 code for low temp reading/failed temp sensor...

To update I replaced the pressure regulator just to give that a shot. I then drove it around about an hour and probably for 75miles. I thought I'd solved my issue but then got a block from home and the CEL appeared, same codes.
Its very cold outside so I can't do to much now. What are some other easy replacements or does anyone think I am definitely looking at replacing a fuel pump?

Check for vac leaks, especially at MAP sensor......could have a contaminated/lazy O2 sensor....

Well got home and played around with trying to find a vac leak. I didn't feel nor hear anything. I will spend some more time later it just gets dark early and to doggone cold out. Oh any tricks to locate a leak? thanks techII

Well got home and played around with trying to find a vac leak. I didn't feel nor hear anything. I will spend some more time later it just gets dark early and to doggone cold out. Oh any tricks to locate a leak? thanks techII

Smoke (either like from a smoke machine or alike).
No cigars or cigarettes though ;)

Spraying with brake cleaner sometimes can do the job.
Cleaner gets sucked in and may cause change in engine run.

I suspect you may have a physical problem with the MAP sensor or associated wiring, rather than the sensor itself. Trace the vacuum line from MAP sensor to intake for leaks; also check that it is free of condensation that may be freezing and blocking it in cold temps.
Next check the wiring harness for intermittents , as your problem seems to pop up at random times. With engine running and warmed up, carefully squeeze, and gently tug, push ,wiggle the wiring harness following the MAP sensor through all connection you can. Be careful around rotating parts: if you find the break in the wire, the engine will change and CEL light should come on.
Jeff

Another update to this issue: I have been doing some of the suggestions mention through this thread and still have not found a leak. However while chasing vac lines during removal of the air breather I found a wadded up plastic bag in the snorkel of breather last night, huum. I cleared air way and today plan on removing O2 sensor to clean it if it warms up outside some.

It is blistering cold here and I just do little checks at a time. Do you guys think this could be the problem affecting gas mixture? Anyway I will do a follow up and let everyone know.

Ps what is the easiest way to remove the O2 on backside exhaust and wrench size? I can hardly reach in that back area. Thanks All

Edit to previous. I will not at this time mess with the O2. I plan on just driving it to see what happens.

Took about a 20 min drive and finally it set the CEL again. I guess the obstruction in the breather was not the problem.

Took about a 20 min drive and finally it set the CEL again. I guess the obstruction in the breather was not the problem.

IMO the obstruction may have been the ignitor of your troubles.
Now it's important to know if the failure code(s) is/are the same as before.

You didn't mention the code the CEL set this time.
What fault code(s) did you read?

same codes 34 and 45. the van will start and run good and drive good. however after a while the engine check will come on. it can come on just sitting at idle running for a long period of time in my drive also. the weather is warm for this week so want to really get after it. thanks to all you helping to try and figure out.

same codes 34 and 45. the van will start and run good and drive good. however after a while the engine check will come on. it can come on just sitting at idle running for a long period of time in my drive also. the weather is warm for this week so want to really get after it. thanks to all you helping to try and figure out.

As others already mentioned, the MAP sensor could have been affected by the obstruction of the air inlet. O2 sensor may have tried to compensate, but could be affected by the overly rich exhaust gasses. this sensor may have gotten defective now.

Could you check voltage on both MAP sensor and O2 sensor?
MAP is 1.04V ~1.83V at idle, 4V~4,8V at WOT.
O2 should read 0 mV at idle ~1800 mV utput Voltage. Approx 100 mV (lean) up to 1000 mV (rich) when in closed loop.
Closed loop starts when the engine coolant temperataure is over 149°F for more than 30 secs.

MAP sensor inputs checked good as I had done this last night. I have not checked input from O2. I will do this after work this evening and get back with you.

Oh yeah there is only one O2 sensor and that is located behind motor on exhaust maniford and just has one wire which is purple i believe. The manual says should be one after converter but not.

Are the numbers to check this one wire the same? Would like to have info for this evening if at all possible. thanks again

Since you have a '92 Transport, this is OBD I......the second O2 sensor is only on OBD II vehicles('96 and up)....

Actually, on startup, the O2 can read around 452mv, until it gets hot enough to start working......when it starts working, it will vary between 100 and 900 mv.....AND.....it must have sufficient cross counts....this is the number of times it goes above and below 450 mv in a prescribed amount of time....if cross counts are low, you have what is known as a "lazy" O2 sensor, and should be replaced....

A code 45 means the the car is running rich, and your reading will be above the 450 mv line....

You can easily test your circuit to the ECM, by disconnecting the harness to the O2 sensor......attach a jumper to the ECM side of the harness(not the O2 side)....now hold the end of the harness in your fingers of one hand, and touch the neg battery terminal with your index finger of your other hand(don't worry, there will be no jolt)....your scan tool will show the O2 reading going lean, or low(100mv or lower)....now touch the pos terminal....the scan tool will now show data going rich(high, near 900mv)......this is a good test to check if there is an open in that line or if the ECM is bad.....

If this tests out ok, but the O2 sensor reads rich, and there is not a rich condition causing this, then pull the O2 sensor....you will probably find either a carbonned up sensor from running too rich for awhile(which could have been caused by the obstruction), or a contaminated sensor from a coolant leak......either case, replace the O2 sensor....

Was not able to test O2 tonight due to working late. I don't have a scanner and wouldn't know how to use anyway.
Do I probe into the single wire from O2 and then ground to something with other probe while engine running, or just ignition on. Not sure on this situation. Hopefully you guys can bear with me not up on electrical stuff.

That test is only for use with a scan tool, to test if the circuit to the ECM is ok....since you don't have one, don't bother with the test...it's meaningless without a scan tool....

TechII I am going to just change out O2. Autozone got a good deal on a Bosch for 16 bucks. I think you guys are probably correct on the obstruction leading to "lazying" the sensor. I will keep everyone posted when I can get it replaced and drive.

Changed the O2 sensor and let the van idle for roughly 20 mins. It started idling rough then set off CEL and finally quit. The only difference was I only had the 34 code and not the 45.

I want to give up but I can't.

Changed the O2 sensor and let the van idle for roughly 20 mins. It started idling rough then set off CEL and finally quit. The only difference was I only had the 34 code and not the 45.

I want to give up but I can't.

So now you have to address the MAP sensor and its wiring.

Messed around again to dig into this MAP code issue. Well I thought I'd found the problem because as I was squirting some carb cleaner on back side of throttle body thought I heard a change in idle. I proceeded to pull air breather and check and discovered 2 vac connectors at T.B. that very, very soft and crackled up.

I knew this was going to be my problem and couldn't wait to replace this. What a let down as it not only kicked the 34 code but also the 45 code again. This was after letting it just sit and run in the driveway for about 30mins.

[quote=WelmoedJ;7091358]IMO the obstruction may have been the ignitor of your troubles.

Well finally solved the problem. The air temp sensor which also has 2 vac ports to it and was not functioning properly. Simple little part inside the air breather affects air and fuel.

Thanks to all you for hanging in there with me. 217k looking to get 250K.