91 240 No Start When Warm

Heys guys I have been chasing this problem for a couple of days and here are some of the details.

I have a 1991 volvo 240 NA with LH2.4 and I am having the occasional no start condition.

When I start out on a typical trip the engine is cold and fires right up within a second or so.

However when the engine is warm say after 30 minutes of highway driving and I park the car for a 5 to 10 minutes the following can happen;

Fires right up as if it was cold.
Takes few seconds of cranking but eventually fires up.
And finally will not start at all.

I have encountered the no start condition twice.

The first time I waiting about an hour or so and it fired right up.

the second time I was trying to induce the no start condition and I finally was able to reproduce the no start condition in my garage.

After the first no start condition I installed a new CPS on the car after the first no start incident.

These are some of the things I checked.
1) I have a good solid spark
2) I hear my fuel pumps key on as well as I have confirmed a fuel rail pressure of about 40 psi.
3) After the no start condition occurs it appears the plugs are clean and dry.
4) The injectors do not appear to be pulsing.

Eventually enough time had passed where the car did fire up but I wasn't because of anything I had down while troubleshooting.

When I was trouble shooting I was able to swap out the ICM and ECM with non matching PN components. (didn't make a difference however when I was able to get the car to run it would run with either)

Not really sure what else to check but I am open to suggestions.

Thanks in Advance

Have you checked the fuse in the engine bay? Mine looked fine but the wire was broke causing an intermittent starting problem like that.

vwblue1967 said:

Have you checked the fuse in the engine bay? Mine looked fine but the wire was broke causing an intermittent starting problem like that.

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If you are referring to the junction block in that black plastic case behind the power steering reservoir it seems to be intact

I did consult my Bentley Manual and it lists a bunch of pin out type tests for the Fuel System ECU

The only two tests I was thinking might shine some light on my engine starting problem are The Engine cranking signal test and engine RPM test.

when attempting the first test I removed the ECU and measured the voltage between pin 30 and ground while cranking the engine. The manual says I should be seeing 8 volts min but I was getting something closer to 4. Would this low voltage have any effect on whether the ECU decides to ground the injector circuit and create a pulse?

When the car did finally start up I rechecked this condition again and I was getting about 8 volts.

I am a little hazy on what the ECU would need as input to ground the injector circuit.

smoothdurban said:

... The manual says I should be seeing 8 volts min but I was getting something closer to 4. ...

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This is a pretty good indication you have too little voltage for anything engine-management to work, while cranking. I would, if you, investigate this carefully. Check those starter cables, battery terminals, and the battery itself to find out how a 12V battery gets pulled to 4V while cranking. The fuse for your FI is inside, not on the fender, it is #6.

Art I was hoping you would chyme in.

I had one of those quick disconnect on the negative terminal of the battery. Since this car is seasonal (winters only) it was easy for me to spin loose the connector when the car would sits for weeks on end. But I have a few other seasonal vehicles (motorcycles) and I have found it easier just to use a battery tender so moving forward this will be my plan with this vehicle.

I have removed the quick disconnect and it sure was corroded.

I also noticed that the ground wire for the fuel ECU should be connect to the the forward position of the fuel rail / intake manifold and it was sandwiched with the other ground wire at the rearward position. As it turns out the forward position bolt is stripped so the PO must of moved it to the rearward ground location.

I have since repaired the forward bolt and returned the grounding wire to a new clean location.

Hopefully these minor tweaks do the trick.

On a side note the battery is old. It came with the car when I bought it nearly 10 years ago. I'll need to load test it.

smoothdurban said:

1) I have a good solid spark

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At the coil or at the plug wire?

Reason I ask...I had an intermittent hot-start issue that started out like this...I'd go pick up lunch, come right back out, and the car wouldn't start. Not every time...but every other week or so, it just wouldn't start. I'd wait a minute or two, try again, fires up, and runs/drives normal til the next time.

Eventually it progressed, but I could never nail it down because it was so random. It didn't start one morning when cold, so I swapped the coil and it started up. Was it the coil? A few days later, the no-start-when-hot returned.

Eventually it died at a light one night and it turned out to be the center of the rotor button had caved in, so no spark getting to the plugs. Fortunately I have two 240s, so I had enough spares to shotgun it on the side of the road and found/fixed the issue.

Did you check the codes?

Could be crank sensor. Usual culprit if it doesn't start when warm is leaky injectors, but if you checked the plugs and they are not soaked in fuel then it's not that. Check the fuel pump relay also and clean all the fuse contacts. I take the fuel pump relay out of the plastic box it's in and look a the solder joints on the backside. The big ones that the power runs through when it clicks over. Sometimes those need re-soldering.

towerymt said:

At the coil or at the plug wire?

Reason I ask...I had an intermittent hot-start issue that started out like this...I'd go pick up lunch, come right back out, and the car wouldn't start. Not every time...but every other week or so, it just wouldn't start. I'd wait a minute or two, try again, fires up, and runs/drives normal til the next time.

Eventually it progressed, but I could never nail it down because it was so random. It didn't start one morning when cold, so I swapped the coil and it started up. Was it the coil? A few days later, the no-start-when-hot returned.

Eventually it died at a light one night and it turned out to be the center of the rotor button had caved in, so no spark getting to the plugs. Fortunately I have two 240s, so I had enough spares to shotgun it on the side of the road and found/fixed the issue.

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New cap and rotor (Bosch) so I am certain the spark signal is strong and consistent.

sbabbs said:

Did you check the codes?

Could be crank sensor. Usual culprit if it doesn't start when warm is leaky injectors, but if you checked the plugs and they are not soaked in fuel then it's not that. Check the fuel pump relay also and clean all the fuse contacts. I take the fuel pump relay out of the plastic box it's in and look a the solder joints on the backside. The big ones that the power runs through when it clicks over. Sometimes those need re-soldering.

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No Codes (1-1-1)

CPS was replaced as a precaution as I have never replaced it and it was at least 10 years old (probably original)

Fuel pump relay is newer but fuel pressure was not an issue as I was getting ~ 40 PSI to the fuel rail.

I think it was a combination of my intank pump not functioning and high impedance generated by one of those battery quick disconnects.

This week I have driven the car extensively and I have had no hot starting issues. It start as it should in less then a second of cranking.

I will keep this thread posted of any updates.

Does it run on starting fluid? Click my sig.

Needs more diag. You say there may be insufficient voltage, but then you say steady spark, so that doesn't really add up.

ZVOLV said:

Does it run on starting fluid? Click my sig.

Needs more diag. You say there may be insufficient voltage, but then you say steady spark, so that doesn't really add up.

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I didn't try starting it on starter fluid as I knew the injectors were not pulsing.

I don't really have the ability to measure the intensity of a spark but I could visibly see the plug sparking when the injectors were not pulsing.

Thanks for the link!

You say spark-no injector pulse..!!.? Is there power to the injectors? How do you know the injectors aren't pulsing?

I confirmed there was power to the injectors by using a test light. Test light was ground to the neg battery terminal and either wire to the injector is positive. I used a noid light while cranking and it Didn’t light up so I could only assume the ground pulse to the injector was not being triggered by the fuel ECU

Ok great. Glad to hear a test lamp and a noid light were used.

Hmmm. No injector pulse....?It could still be crank sensor related.

Look at a wiring diagram. Ezk and LH get their power from the same source.....I would say to shake down that power circuit.



http://s796.photobucket.com/user/ZVOLV/media/EFI Swap/lh24.jpg.html

As this is a seasonal vehicle I give all the fuses an annual inspection and clean / replace fuses as needed.

Are ground point 2 & 3 on the intake manifold / fuel rail?

If so I cleaned these and address some issues I had with them as they were double up on one grounding point.

So far the car has not left me stranded and fires up in all conditions.

My 92 240 LH 2.4 had very similar symptoms, when the ignition module began failing

a) stall and/or wouldn't start after approx 30 min running time ( later would start again in an hour or so )
b) codes 1-1-1

Otto Mattik said:

My 92 240 LH 2.4 had very similar symptoms, when the ignition module began failing

a) stall and/or wouldn't start after approx 30 min running time ( later would start again in an hour or so )
b) codes 1-1-1

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I tried another ignition module and it wouldn't start up.

Thus far after cleaning some grounds and removing the battery quick disconnect the engine starts all the time.

I am going call this problem licked. . . . . . . . for now!

Have you tried setting it on fire?

ZVOLV said:

Have you tried setting it on fire?

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No need for that!

The 242