OK, here's an interesting one. My '91 740 Turbo was running just fine 2 days ago. I had to go to a city just north of me for a part of my A/C that needs replacement. It takes me about half an hour to get to the destination, but they didn't have the part and I went back south to a Volvo specialist for the part. While parked at the shop with the specialist, I was trying to leave and the car would not start. It will turn over when i try to start it, but will not run.

I ended up having the car towed back home instead of having the specialist inspect it (the inspection bill alone is more than I can afford) and I have access to a lift at the college that I go to.

Yesterday I spent about an hour looking around the car to see if there were any issues with the fuel lines (leaks) and found nothing. I then attempted starting the car and it ran, but about 20 minutes later it died and would not start. I did the same thing today, about half an hour ago, and it did the same thing. I put a little bit of STP fuel stabilizer and injector cleaner in the tank and before I let it run (I didn't use the whole bottle of either). The temperature gauge reads normal and never goes above normal operating temp. My first thought is that there is no fuel getting into the cylinders. It is very similar to when I had vapor lock a few years ago, but the weather conditions were not the same. If it helps a bit, it was pouring rain when it first died (making me think that water got somewhere.

Any ideas?

 

Hmmmmmm, reading other issues that are similar I will look at the fuel pump relay. I don't recall hearing the fuel pump when it stalled. I'll check when it stops raining.
EDIT: I made it stall again and will not start. The lower left relay was pretty hot. I can't find relay diagrams to see which one. Help please.

 

a 91 740 turbo, the fuel relay should be the larger one in the middle row on the left side.

 

Ok, pulled it out. I'm on IPD and am not sure which of these to buy.
Volvo Fuel Pump Relay 240 700 900 AFTERMARKET 113772 1323643, 1347603 3523608E, 3523608
Volvo Fuel Pump Relay 240 700 900 STRIBEL 104561 1323643, 1347603 3523608T, 3523608, 1347603, 1323643
https://www.fcpeuro.com/products/vol...80-940-3523608

 

Stribel was the OE supplier for these relays. KAE is probably OK too. noname chinee? no way.

 

OK, thanks. I managed to pull the relay and took the cover off to look. What I found is that the portion of the relay above the diode was a little sticky. Fortunately I was able to clean it up and it does not stick anymore. I reinstalled it after another inspection from my parents, they did electronics in the Air Force, and it seems to work just fine. I am currently waiting for a crank position sensor to arrive in the mail and will install it and update you on that.

EDIT: Car works just fine now. I received the crank sensor today and installed it and the car works like it did before, just without the stalling.
On another note, I was reading about some mechanic that has replaced many of these sensors and says that he can replace one in under 10 minutes. I replaced mine in under three minutes . It was easier than the sensor that I had to replace on a mid 90's Jeep Grand Cherokee, which involved two people and a lot of 3/8s extensions.

 

Update: Car died again today after leaving my local college to get home.
The first time today I had trouble starting the car was when I was servicing my A/C. To put the hose onto the service fitting, I had to unmount the ignition coil (because the service port is in a stupid place). The car took a bit to start up, but eventually ran. I cut the car off and went to work on the A/C again. Was done and tried to start it again and it would not run. I adjusted the coil a bit and the car then started up and I went about my business until I cut it off again when I was done. A few hours later I left the college and was on my way home.
I went a whopping one mile when it died. It misfired for about 10 seconds before it died. Fortunately I was at a red light and was able to turn into a parking lot to look for the issue.
I, again, found nothing wrong. I looked at the spark plug wires and the coil to distributor wire and they seem fine (there was water in the plug that goes from the coil to the distributor on the distributor side, not sure if that is something important). The car started up finally, after about 10 minutes of starting attempts and threats to murder the car, and I managed to drive it the rest of the six miles home. The fuel pump relay got warm. It was not too hot to touch, just warm to the touch. I purchased spark plugs from a local store and installed them, I had BOSCH and replaced them with autolite (no idea about that brand), only because it could be the plugs seeing that they have 20k miles on them. What else could it be? My electronics specialist father claims that it's the fuel pump relay, but I heard the fuel pump turn on when the car would not start. I think it could be the spark plug wires and coil wire (they are as young as 1993, when the distributor was serviced, or are original to the car). Could it also be an ignition coil issue?

 

Logic points to the coil work you did: retrace your steps, make sure everything is connected right.

Those wires, plugs, are not optimal but they should not make the car not run, may be run not well but still run... Get Bougicord wires, NGK plugs gapped at .28-.32. How are the dist. cap, rotor, etc?

Not sure what you mean by "water in the plug that goes from the coil..." but yes, any water in those parts would cause problems.

 

I replaced the cap and rotor two months ago.
The water in the plug is the one connected to the distributor.
I also spaced the plugs at 0.028 inches.

 

water anywhere in a high voltage circuit is the enemy. the wire from the coil to the distributor cap center is the main high voltage. I'd use a compressor and blow it dry, and if there's significant corrosion replace. after drying it, put a bit of silicone dielectric grease around the outside of the post .

I second the motion re: Bougicord spark plug wire sets for these cars, and NGK plugs. you want plain copper plugs, BP6ES... or BP7ES for turbos that are driven hard.

 

Ok, looking more into my issue I may have found the problem(s). The relay could be bad, causing the stalling and not starting for a while. Or the main pump could be bad, drawing too many amps through the relay and causing it to fail and the engine to stall. I just might replace both, one at a time though, to see what the issue is.

 

do note, there's two fuel pumps, both driven by the same relay. the main pump under the car delivers the actual fuel pressure, and the in-tank helper pump keeps the main pump supplied with fuel. the tank pump is on its own fuse, while the main pump is on the main FI fuse along with the rest of the ECU etc.

 

I do know that pierce. I replaced the in tank pump a few months ago because the old one was nearly locked up. I checked both fuses to the main pump and tank pump and they have not blown yet.

 

As of two days ago my 1990 780 (B230FT: same as 740/760) started cutting out. It waits until I'm a couple of miles from home of course, and then dies, quickly. On those occasions when I have watched the tachometer, it drops like a stone as the engine dies. It will die at idle, and under power. It also occasionally hiccups without dying. I have also seen the tachometer blip up once when the engine hiccupped. Fortunately, restarting is fairly reliable, but I am likely to have the engine die six to eight times on the way home, which suggests engine temperature may play a role.


The 1990's era Diagnostics give me one code: 2-3-2 "long-term fuel trim either too lean or too rich".

So far, I have:
Changed out the fuel pump relay.
Changed out the crank position sender.
Cleaned the throttle body (because I had been planning to do it).
Reset the Throttle Position Switch.

I'm not sure what my next step should be. I tested both TPS's getting resistances of 173 (old) and 185 ohms (now installed). The Idle Air Control may be a little shaky, but it throws no codes. The car is kept garaged, and rarely sees rain.

Any suggestions would be welcomed.

 

does the code come back when you reset it ? if not, it might be an old code and not pertinent to whats happening now.

if its persistent, 2-3-2 is often caused by air leaks between the MAF/AMM and the intake manifold. On a turbo, especially, this is a long path, as it includes the turbo fresh air plumbing, and the intercooler.

 

How are tune up items like plugs, wires, cap rotor, etc?
You may have a main fuel pump going out, (heats up, acts up).
Grounds for the FI may be the cause.
Weak/bad Power Stage would do what you describe, too...
Sorry I cannot be more specific.

 

Pierce, you caught me. The code didn't set the CEL, and probably dates back a year when I had the turbo outlet hose blowing off. I never looked at the code then, and so wouldn't have reset it. So as you say, not pertinent unless it now comes back.


Lev, plugs, wires, rotor, cap all new within the last 2 years (maybe 6k miles on this). The power stage is an interesting thought. I'm using an MSD Blaster SS coil. Could this be overpowering the stock power stage? How would I test the power stage? I'll check out the Fuel Injector grounds.


Thanks for the inputs.

 

This morning, after running the engine until it died a couple of times, I find that the 2-3-2 code is back. Long-term fuel trim is either rich or lean. No other codes.

I've checked the entire intake air path for leaks and found none. All hoses, connections, and pipes from the MAF to the throttle body are sound, and I can hear or feel no leakage from the charge air cooler.

I actually bought a new Fuel System Relay (stamped 12/9/2014) from the dealer, to no avail, so now I have three that perform equally (one from 2002 and one no-name no-date). Both fuel pumps run with the key moved to position II. I swapped out the Idle Air Control to no avail.

The problem doesn't kick in until the engine gets to or near to operating temperature, but then after cut-out it can normally be restarted immediately, with progressively shorter times to next failure.

O2 Sensor?
Injector seals?
Fuel pressure problem (with pressure regulator or pump origin)?
Coolant temperature sender? (Gauge appears normal)

Any further suggestions or recommendations on where to start?

 

I'd be verifying you're getting spark when its in the 'no start' condition. As lev suggested, a bad power module often fails when it gets hot, then works again when it cools off. the power modulator is like an amplifier between the ignition control unit and the ignition coil. dead modulator == no spark. on a 7/9 turbo, its located forward of the left wheel hump up against the inside of the fender, near the ABS modulator. its a fairly small little module bolted down with a plug nearly as large as the module.

another test would be to plug a "noid light" into one of the fuel injectors. this should blink each time the injectors fire, so if it doesn't blink when you crank it while in the no-start condition, you might check the 'radio noise suppression relay', which is also on that same fender not far from the ABS unit, this relay provides the power to the fuel injectors.

 

O2 sensor? NO
Injector Seals? NO
Fuel Regulator? NO
Coolant Temp. Sender? NO

Fuel pump? Possibly.
Test the fuel pressure. Easiest way, when you stall, open the Schrader valve and see if you get a healthy squirt, I bet you don't.