Will not start/run after it warms up

Tiny
ARKAYIC
  • MEMBER
  • 1989 CHEVROLET CELEBRITY
  • 2.8L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 139,000 MILES
I bought this car about three weeks ago, ran decent during the test drive, lack of power but it ran.

When driving it home, it drove about thirty five to forty miles, engine seemed to start getting choked up and started surging and shutting off and I started to lose speed, went from sixty to forty in about ten seconds, pulled over and it would not start back up. Did not even try. Had it towed home. Went out the next morning started up great, tried driving it in a parking lot next door, within five minutes it shut off again. Checked the codes for the CEL, got code 43. Replaced the knock sensor, 43 went away but still would not start while at operating temperature. No CEL or codes at this time.

I changed the fuel filter because it was old and clogged (hard to blow into) tested the fuel pressure at the rail. Steady 38 pounds, when it would shut off it would shoot up to 45. So not the fuel pump.

I took it to a shop and asked them what they suggest I look at, they said fuel pressure regulator.

I replaced the regulator, still no change. Runs a little longer but still surges and sputtered. Checked codes again even though there was no CEL and got code 33 at first, then later that day code 34 popped up too.

33 and 34 is high and low vacuum at the the MAP sensor. I replaced the vacuum lines thinking maybe I broke one and unplugged the low coolant sensor. Ran great with no issues, so much so I even drove it to work. On my way home, started hesitating and surging again and shut off in the middle of traffic. Replaced the MAP sensor. Still no dice. I am at a complete loss as to what could be wrong.

Pretty sure the reason I got this car as cheap as I did was no one could figure it out.
It appears to have:
New re-manufactured ECM.
New IAC sensor(but idiot before me put it in cross threaded and loose).
New TPS.
New EGR.

Has new:
Map sensor.
Fuel filter.
Fuel pressure regulator.

I do not even know what to test or check now. Please help me out with some ideas and advice.
Do you
have the same problem?
Yes
No
Wednesday, December 20th, 2017 AT 8:38 AM

16 Replies

Tiny
CARADIODOC
  • EXPERT
Part of what you described is often caused by a collapsed pick-up screen inside the gas tank. The clue is the engine runs best at highway speed, and tends to stall when the highest volume of fuel is being pumped, which is during coasting. Sufficient volume cannot get through the screen, so pressure drops. You can identify this by attaching the fuel pressure gauge where you can see it while driving, and watch what happens to pressure when the problem occurs. If the pressure drops, you may be able to overcome the problem by disconnecting the vacuum hose from the fuel pressure regulator and plugging it. That will cause pressure to increase and reduce the volume of fuel the pump needs to pass.

The idle air control valve is not a sensor, and it cannot allow any air to leak in. Chrysler is the only manufacturer that never needed a mass air flow sensor to make their engines run right. All other manufacturers use that sensor on all or most of their engines. If there is a leak in the fresh air tube between the sensor and the throttle body, or a vacuum leak anywhere else, that air will not go through the sensor and will not be measured. No fuel will be calculated to go with that air. Those leaks can cause a stumble, hesitation, stalling, all the way to a crank/no-start. A clue is the engine will fire when starting fluid is sprayed in at the air filter, proving you have spark.

When you have a mass air flow sensor, the MAP sensor is used to measure barometric pressure, and as a back-up strategy when a problem with the mass air flow sensor is detected.

You should be checking for loss of spark too. Most commonly you will also have no injector pulses and the fuel pump will not resume running during cranking. Typically that is caused by a failure of the crankshaft position sensor or the camshaft position sensor.

For the fault codes you listed, your best approach is to watch their readings on a scanner during a test-drive. For two contradicting codes, start by looking for a rubbed-through wire that got cut where it lays over the sharp edge of a metal bracket, and corrosion between mating and adjacent terminals in electrical connectors.

One more thing to consider is the fuel pump only runs for one second when you turn on the ignition switch. It resumes running when the engine Computer sees signal pulses from the crank and cam sensors, meaning the engine is rotating, (cranking or running). On older GM products, the fuel pump resumed running from a tap on the oil pressure sending unit. If you lose oil pressure, the fuel pump turns off. That is a safety system in case a fuel line gets ruptured in a crash, to prevent pumping raw fuel onto the ground where it would become a fire hazard. It was fairly common for stalling to occur from the fuel pump turning off due to low oil pressure or a defective sending unit. Oil level that is just one or two quarts low can cause this long before the pressure gets low enough to trigger the "oil" warning light.
Was this
answer
helpful?
Yes
No
Wednesday, December 20th, 2017 AT 3:29 PM
Tiny
ARKAYIC
  • MEMBER
I did hear about the quart low oil thing from a Chevrolet friend, but it is slightly overfull and still no dice, and it is not on a hill. When I tested the fuel pressure it never read below 38, once it was warm it would shut off shortly after start up and go to 45. With gas at the rail I do not think its the delivery system. I pulled a spark plug and you can see that it is firing but looks almost like it is not getting gas. But still has correct pressure at the rail when warm. And we also tested spark with a rubber handled screwdriver from the wires. Gets spark at all times. I wish I had a scanner but I am honestly way to broke for the cable and scanner. And this type car does not seem to have a MAF sensor. The only vacuum line from the map sensor is to the fuel regulator which tit is off to the TBI. And I have spent hours checking wires and just tracking down everything and I can find no issues or breaks in the wire harness cover.

One thing to note, because it is making me think more and more towards the fuel injectors maybe, is if you hold it at half throttle and try to start it, it will start and rev but will immediately die the second you let up the gas completely. But fuel injectors are $40.00 each, so is it possible to check the fuel injectors with the key on but no crank with a multi-meter?

One thing I do not think I mentioned very clearly is that on a fresh morning after sitting it will start up and drive for about ten miles before it gets warm and then shuts off wherever you are, sitting at a light or going up a hill at 35.
Was this
answer
helpful?
Yes
No
Thursday, December 21st, 2017 AT 5:55 AM
Tiny
ASEMASTER6371
  • EXPERT
Good morning.

When you checked the fuel pressure, did you check it when the car shut off to verify you are not losing pressure causing it to stall? This would make sense as the other codes are related to lean and rich conditions.

Roy
Was this
answer
helpful?
Yes
No
+1
Thursday, December 21st, 2017 AT 8:15 AM
Tiny
ARKAYIC
  • MEMBER
Yes I did. Checked it running and as it shut off and when just sitting there off. Even ohms checked the fuel injectors wires to make sure the ECM was not going haywire once it warmed up with fuel pressure test reading 38-45. No faulter.
Was this
answer
helpful?
Yes
No
Thursday, December 21st, 2017 AT 12:16 PM
Tiny
ARKAYIC
  • MEMBER
Checked a few things more after talking with a local mechanic; blocked vacuum to the charcoal canister, no help, tried unplugging coolant temperature sensor, no change, blocked vacuum to cruise control. Nothing. When cranking it wants to turn over, you can hear compression trying, but will not start when it is above 150 degrees.
Was this
answer
helpful?
Yes
No
Thursday, December 21st, 2017 AT 1:39 PM
Tiny
ASEMASTER6371
  • EXPERT
I was just thinking. The ignition modules were a issue with these. You can remove it and have it tested at a parts store. That is a free service as well.

Roy
Was this
answer
helpful?
Yes
No
Thursday, December 21st, 2017 AT 2:10 PM
Tiny
CARADIODOC
  • EXPERT
Your engine does have a mass air flow sensor, and if it fails, you'll still have spark. Try banging on it, then cranking the engine. If that works, the sensor has bad solder connections inside. More commonly, when the engine is idling, banging lightly on the mass air flow sensor will cause the engine to stall.

When the mass air flow sensor fails, the MAP sensor is supposed to become the back-up strategy to allow the engine to run poorly, but run. GM had a huge failure rate in the late '80s with their MAP sensors, so they sold them to Chrysler. With a failed MAP sensor on a Chrysler product that got towed in, we often surprised owners by driving the vehicles into the shop under their own power. The secret was the engine would continue to run as long as the accelerator pedal was moving. Direction and rate of change didn't matter; it just had to be moving. I don't know if that works on GM engines. MAP sensors of that original design are all long gone. The redesigned sensors are pretty reliable.

Hi Asemaster6371.
Was this
answer
helpful?
Yes
No
Thursday, December 21st, 2017 AT 5:27 PM
Tiny
ARKAYIC
  • MEMBER
This vehicle does not have a Mass Air Flow sensor. I have triple checked.

Ignition module. Hmmm now that I have not tested nor looked at, but with a quick check on google. I think you may have a golden idea there. I will go look and test this and get back with updates.
Was this
answer
helpful?
Yes
No
Friday, December 22nd, 2017 AT 6:08 AM
Tiny
CARADIODOC
  • EXPERT
You're right. One of my sources shows the MAF sensor for your engine available from four sources. Another source doesn't show that sensor. Sorry about that.

This makes the MAP sensor your main fuel metering contributor. One thing to be aware of is the normal range of signal voltage is 0.5 to 4.5 volts. Anything outside that range is what triggers a diagnostic fault code. If the sensor develops the wrong voltage, it will not set a fault code as long as that voltage stays within the acceptable range. A tenth of a volt off will cause a big performance problem. Besides a failing sensor, keep an eye out for a dry-rotted vacuum hose, condensed fuel vapors blocking the hose, and vacuum leaks.
Was this
answer
helpful?
Yes
No
Friday, December 22nd, 2017 AT 11:59 AM
Tiny
ARKAYIC
  • MEMBER
Well. I replaced the ICM. Ran amazing with no surging or bogging down for about 15 minutes. Turned it off to see if I could restart it. Wouldn't start. Ran a code check, no codes at all. I'm completely at a loss here.
Was this
answer
helpful?
Yes
No
Thursday, December 28th, 2017 AT 3:21 PM
Tiny
ARKAYIC
  • MEMBER
I tried spraying carb cleaner in the tbi, and it seemed to start maybe for half a second.

So should I next check fuel injectors? When checking FI can you check them by turning the key with no crank or do I have to crank it?
Was this
answer
helpful?
Yes
No
Thursday, December 28th, 2017 AT 4:08 PM
Tiny
ASEMASTER6371
  • EXPERT
Ok

Did you check the fuel pressure as I suggested back a bit when it shuts off?

Did you also inspect the connector to the ICM? That was a know issue back in the day.

HI CJ hope all is well with you
Was this
answer
helpful?
Yes
No
Thursday, December 28th, 2017 AT 5:12 PM
Tiny
ARKAYIC
  • MEMBER
Fuel pressure was checked when it shuts off, and when it was cold. Read 38 constant only moving upwards to 45 when it stalls out. But never falls below 38 ever.

I did speak with a mechanic who said that fuel pump could be failing when it's warm even without showing a drop in pressure(he had same car, same problem) but I'm worried to drop another 50$ on a fuel pump when pressure never seems to be an issue.

One note I've made though, is with correct pressure at the rail, could the injectors be bad since they come after the rail? Read another thread where a guy had similar problem and ended up having three injectors not working properly.

The connectors looked good, no cuts or splits.

It does not seem to surge and bogg down since Icm change, but I may have not noticed it yet. But still won't start after it reaches 150 degrees
Was this
answer
helpful?
Yes
No
Friday, December 29th, 2017 AT 12:42 AM
Tiny
ASEMASTER6371
  • EXPERT
Ok, the pressure is too low. Should be 45 lbs constant. 38 is not good enough.
You will need to replace the pump.

Roy
Was this
answer
helpful?
Yes
No
Friday, December 29th, 2017 AT 6:43 PM
Tiny
ARKAYIC
  • MEMBER
Ok so with the issue centering around temperature, I figured I would replace one of the only sensors I had not tested/replaced, coolant temp sensor. Drove it around for bout three hours so far with no surging/bogging, no dying(might still have issue with iac valve, stalled once coming to a stop.) Got to 190 degrees, turned it off and it started right back up numerous times.

13$ sensor was the whole issue. Can't believe it. Thank you Roy and CJ. Without your advice and input I would never have came to figuring this out.

If this doesn't end up being the end of this loop, I will be back!
Was this
answer
helpful?
Yes
No
Monday, January 1st, 2018 AT 11:38 AM
Tiny
ASEMASTER6371
  • EXPERT
Your welcome. We are hear to help
Was this
answer
helpful?
Yes
No
Monday, January 1st, 2018 AT 11:41 AM

Please login or register to post a reply.

Recommended Guides