91 740 Turbo (actually a 740 SE, a model which some people have informed me does not exist )

Last week while driving around town, it sputtered and did nothing when I put my foot down on the accelerator at one point. Then after a couple seconds, it seemed to respond normally. Then upon parking and shifting into Park, it died. Failed to start. Then a few minutes later it started and I drove it into my mechanic.

Mechanic (not a Volvo specialist, but I have had good experiences with his shop before) could not replicate the problem and could not get "codes". He advised that these intermittent problems can be very tricky and advised me to stay local and bring it back in if the problems persist or get worse. He did not charge me anything.

Today (one week later) it flat out died while on the road. Then it wouldn't start until the third try. Drove it into a parking lot 50 yards away, and it died a second before I would have shifted into park. Then we did some more grocery shopping (have been hungry these days ), came out and the car started just fine and we arrived home with no problems.

If my mechanic can't figure it out this time, I will take it to an excellent Volvo specialist, who is unfortunately about 20 mins away.

Any ideas what this might be? Mechnic suggested fuel pump or filter. I'm also wondering about injectors??

Thanks.

 

You have the SE with the ground effects and the rear spoiler, etc? I had one; mechanically it's a regular 740 T.

First:Crankshaft Position Sensor. Second: Fuel Injection Relay.

Fuel Filter? No way!
Fuel pump? Remote chance.
Injectors? No way!

 

Agree - check the crankshaft position sensor. It is located on the top of the bell housing where the engine and transmission meet. It has a fat black wire coming off of it that is the size of coax cable and runs to a connector on the firewall. Next time it dies, wiggle this wire to see if it helps. If the insulation on this wire is cracked and flaking off, then it is time for a replacement.

Second/third checks would be the fuel pump relay and the radio suppression relay.

 

Interesting. Thanks for your replies.

Yes it is a 740 SE with the ground effects and spoiler. The car is completely red on the exterior, giving it quite a different (much sleeker) appearance than a standard 740 (which had black bumpers). The dealer told me that Volvo only made 500 (or was it 1000?) of these as a special edition (for California only). It also has a full leather interior, sunroof, and beautiful wood trim. In fact, at the time, the interior was better looking than the 960. When it was new, many people didn't even recognize it as a Volvo. To me it always sort of looked like an Aston Martin Lagonda.

The interior and exterior look pretty crappy these days, and I've contemplated getting it painted, and the interior trim fixed up, etc. But of course, to do this right is very expensive (was quoted $4500 for paint alone), and my main rationale for owning this car is that it is extremely cheap to own/operate. It also has very low miles for its age (~150K), as I've always lived close to work. My mechanic told me that mechanically, everything looks shockingly good given the age of the car.

The CPS idea is interesting, because the tach needle sometimes is twitchy, flicking back between 0rpm and 1500 or higher in a split second. At times it has gotten stuck at 2500 or so--but it was clearly only the needle and not the engine itself. I chalked this up to general weirdness of the electronic/instrument cluster (have had other problems in the past). But, maybe it is the CPS and not the cluster itself??

 

I doubt that the crank position sensor would cause the weirdness in the tach unless you also felt the engine running funny at the same time. The CPS provides the signal to both the fuel injection and ignition computers. The ignition computer provides the signal to the coil to fire the plugs. I believe it is the same signal going to the coil is the same that drives the tach (but I could be wrong as I am more familiar with 240s).

 

the CPS signal goes to the ICU, which cleans it up and sends it to the ECU, the coil, and the tach.

 

My 87 740 turbo has been doing the same thing. Ill be driving and it starts to sputter, if I gas it all the way it will sometimes work but usually, it dies. It starts back up after trying a 3 to 5 times. It happens randomly to where days will go by with no problem but when there IS a problem, it dies over and over again while on the road or at stops. The car will still be "on" with the dashlighs working and everything. Someone also suggested the fuel pump may be the issue. I feel like i constantly hear a ticking in the fuel rail. I think ill check out the fuel pump and Cps.

Sounds like a pretty similar problem!

 

an 87 is LH 2.2, and doesn't have a CPS.

I would check your fuel pump relay first before messing with the pumps. make sure the pumps are being powered when its in this no-start condition.

um, on these random days where it fails, is your fuel relatively low, like below half a tank ? if so, then it might be the in-tank fuel pump.

 

Do you think a good Volvo specialist should be able to definitively diagnose and fix the problem, even if they can not replicate the problem (i.e., if the car behaves normally for them)? My local (non Volvo specialist) said that it would have to fail for them before they could figure it out or get the codes...

 

yeah, thats the problem with old cars. mechanics want to be able to bill for procedures, just like doctors. time spent on diagnosis is a black hole.

I try and diagnose my problems and if the fix is beyond my current means or time (for instance, a head gasket), I'll take it to my mechanic, explain my findings, and have him fix it. I bring him the parts I want him to use too, so my jobs generally are real easy for him, he writes me a fair bill. he's not a volvo specialist, he does major engine and transmission work on a wide of older imports, and some hot rods too (I've seen him drop hotrodded crate motors into a few old american iron), but his personal love is older jaguars.

 

update:

Took the car to a Volvo specialist, but the car ran fine for the two days he had it. He agreed the culprit might be the CPS, so I had this replaced ($180). It ran fine for a few days after this, then would not start after repeated attempts. I had the car towed to a third mechanic who looked at it right away, swapped out the fuel pump relay, and it started immediately. Three weeks later with the new fuel pump relay and the car is running fine...

 

CPS for $180? It's a $40 part and 1 minute swap time.
FI relay was my second guess....

 

I wanna see some pics.