Volvo 760 GLE 1990 G Reg. Need help/advice/pointers

[diccapilly]

Hello all.

My 760 GLE needs some help to get her moving again. If you can give some help/advice/pointers on the following account of events that would be most appreciated.

It all started with her hunting when taking off at junctions after a 4 ish mile run. Managed to get her home and found that the distributor cap was damp so I assumed that was the cause of the hunting.

So I dried out the distributor and took her for a spin a few days later. It all seemed to be fine and I believed the problem was solved. But then the hunting began. The engine eventually cut out and I was unable to start her again. This time I was sadly some distance from home.

Eventually the RAC attended and tested the spark plugs, distributor, rotor arm, HT leads and found that the coil was not receiving 12V, so he made up a ‘fly-lead’ and connected one end of the fly-lead to the positive battery connector and the other end to the positive ignition coil connector. Sadly that did not start the car. That was Friday 23rd Feb evening. The car remains there and the RAC said they will tow her to a garage but I am trying to fix her myself if I can.

I became confident that a new coil was going to correct the problem because on the Friday evening the RAC mechanic noticed that the sparks from the HT leads, were orange and pointed this out to me. I saw them too and they were definitely orange. Reminded me of a tequila sunrise. Anyway, it was not until Sunday that I read on the WWW that the sparks should be blue else they are not sufficient to ignite the fuel. So you can see why I thought a new coil would be the answer to all my woes.

Ordered the new coil Monday and collected the new coil today. Fitted the new coil, sadly the engine is still not catching.

The engine is turning over nicely, the battery was replaced in September 2023. There is now no spark at all. Thinking the new coil might be faulty I swapped the new coil to the old coil to see if I was getting the orange sparks but no, nothing. No sparks, orange or blue from either coil.

So far I have replaced the distributor cap, spark plugs, coil (NGK 413660010) and rotor arm, in that order.

Any ideas?

Thanks and best wishes, Steve

[SalvadorP]

This could be a faulty crank position sensor that eventually just died.
Do you have a multimeter to test the sensor?

EDIT: Something else comes to mind to. You did say the distributor cap was damp. Can it be that the distributor itself failed?
Are you sure you are getting fuel?
Either way, I would test the CPS first. I've seen so many people scracthing their heads with issues just like yours, fire the parts cannon and in the end it comes out to the CPS, which so many people so often fail to check/replace.

[diccapilly]

Originally Posted by SalvadorP

This could be a faulty crank position sensor that eventually just died.
Do you have a multimeter to test the sensor?

EDIT: Something else comes to mind to. You did say the distributor cap was damp. Can it be that the distributor itself failed?
Are you sure you are getting fuel?
Either way, I would test the CPS first. I've seen so many people scracthing their heads with issues just like yours, fire the parts cannon and in the end it comes out to the CPS, which so many people so often fail to check/replace.

Yes, I have a multimeter and I have a Haynes for the 760. I'll consult the manual tomorrow regarding how to test it. But I may just buy a new CPS. If I can get my hands on one. I am pretty sure my one is in a poor state - I suspect it should have been tested/replaced ages ago.

RE: testing the sensor. Is it a case of continuity?

I have replaced the old distributor cap with a new one. I must admit that I just assumed I was getting fuel. There certainly is petrol in the tank and my wife complained about the petrol smell when I was enthusastically trying to get her to start. But that is no guarantee.
Is there an easy way to determin whether fuel is being fed?

Thanks for getting back to me - really appreciate it.

[SalvadorP]

Originally Posted by diccapilly

Yes, I have a multimeter and I have a Haynes for the 760. I'll consult the manual tomorrow regarding how to test it. But I may just buy a new CPS. If I can get my hands on one. I am pretty sure my one is in a poor state - I suspect it should have been tested/replaced ages ago.

RE: testing the sensor. Is it a case of continuity?

I have replaced the old distributor cap with a new one. I must admit that I just assumed I was getting fuel. There certainly is petrol in the tank and my wife complained about the petrol smell when I was enthusastically trying to get her to start. But that is no guarantee.
Is there an easy way to determin whether fuel is being fed?

Thanks for getting back to me - really appreciate it.

To test the CPS there many are tutorials online and on youtube.
To test if the fuel is getting to the rail. I guess the less involved way and without a fuel pressure gauge would be to disconnect the fuel pressure regulator fuel return hose, put it inside a clear plastic container and crank the engine a fe times. That doesn't prove the injectors are working though. But at least you will know it's not the fuel pump/pumps. Don't know if you car has 1 or 2, I suspect it must have 2 like the 740/940.

Have you inpescted the spark plugs for any clues?

[Forrest]

Have you tried a new or known good fuel pump relay? It supplies power to more than just the fuel pump. In fact, I’m pretty sure it provides power to ignition related components, possibly including the ECU. This could explain why you still had no start when the LT connection to the coil was jumpered.

[SalvadorP]

Originally Posted by Forrest

Have you tried a new or known good fuel pump relay? It supplies power to more than just the fuel pump. In fact, I’m pretty sure it provides power to ignition related components, possibly including the ECU. This could explain why you still had no start when the LT connection to the coil was jumpered.

On that line, another point of possible failure is the injector resistor pack.
That would be easy to diagnose. Big screw driver tip on the manifold and an ear on the handle. If the injectors are firing, it's not lack of energy to the injectors.

But I still think the fact that there was smell of gas, kind of indicates that there is gas being delivered to the engine. It's just not firing either due to an ignition issue, a fuel delivery issue at the injector level or a bad cps. Just my 2 cents.

[diccapilly]

Originally Posted by SalvadorP

To test the CPS there many are tutorials online and on youtube.
To test if the fuel is getting to the rail. I guess the less involved way and without a fuel pressure gauge would be to disconnect the fuel pressure regulator fuel return hose, put it inside a clear plastic container and crank the engine a fe times. That doesn't prove the injectors are working though. But at least you will know it's not the fuel pump/pumps. Don't know if you car has 1 or 2, I suspect it must have 2 like the 740/940.

Have you inpescted the spark plugs for any clues?

Spark Plugs:
When I first experienced the hunting and dried the distributor cap I looked at the plugs. They looked a bit lighter than 'normal'. 'normal being off-white, brownish colour as shown in the Haynes Manual.
When the engine refused to start and just after I changed the old distributor for the new one the same plugs looked sooty.
I have since changed them for a set of Champion, which were on the car before the most recent spark plug change. I've not checked them since the last bout of trying to start her up. Will look in on them... next time I get to the car.

I'll take in the tutorials re: testing the CPS.
Thanks for the info re: fuel return hose.
I believe it has two pumps. 1 under the car and one in the fuel tank.

[diccapilly]

Originally Posted by Forrest

Have you tried a new or known good fuel pump relay? It supplies power to more than just the fuel pump. In fact, I’m pretty sure it provides power to ignition related components, possibly including the ECU. This could explain why you still had no start when the LT connection to the coil was jumpered.

The fuel pump relay in use during the original hunting was fine as far I as know (unless it was the cause).

I do have a known 'good' spare which I have tried since being unable to start her and is still in situ.

It is conceivable I suppose that the known 'good' spare has developed a fault, so I should take that into consideration. Especially if it interacts with the ECU.

I like to think that a new CPS could be the answer. Mainly because replacing it is something I can manage. I can safely say that the current CPS has not been renewed in the last 17 years.

[diccapilly]

Originally Posted by SalvadorP

On that line, another point of possible failure is the injector resistor pack.
That would be easy to diagnose. Big screw driver tip on the manifold and an ear on the handle. If the injectors are firing, it's not lack of energy to the injectors.

But I still think the fact that there was smell of gas, kind of indicates that there is gas being delivered to the engine. It's just not firing either due to an ignition issue, a fuel delivery issue at the injector level or a bad cps. Just my 2 cents.

I'm making the CPS replacement a priority.

[Rob1950]

I had a starting problem with my 940 just after I bought it. It turned out to be a crankshaft sensor. Starts fine after replacement. My issue now is uneven tick over. It sometimes ticks over at 500rpm, or at 1500 or 2000 or waves up and down between 1000 and 2500 or stalls. Somethings sticking. Restarts fine. Booked in for next Tuesday.