Greetings enthusiasts and thanks for taking the time to help me with my newest problem. I have an 87 Volvo 740 GLE that is always keeping me on my toes with new problems and issues. It has surprised me with a new issue just before I'm about to leave on a road trip. The car starts up perfectly but when moving at slow speeds (turning corners and stop lights) it can randomly die. My first thought was a dirty throttle body, as I've had this issue before, but the engine does not sputter and then die as it did when the TB was dirty. Rather the RPMs drop to zero suddenly and tapping on the gas pedal does nothing to help. Once I've coasted to a stop and put the car into park, it turns over just fine and drives just as well...until it randomly dies again.

I've done some research on here and other forums and I believe the problem lies either in my distributor or the fuel relay. What I could use is some advice on how to assess the distributor to determine if this is the cause of the problem before purchasing a new one. I've seen new distributors ranging from $130 to $350 and I'd rather not spend that much only to find the distributor was not the issue.

Any advice on my current mechanical issue would be greatly appreciated. Thanks in advance!

 

This could be timing related, the timing on a LH2.2 (pre 1989) system comes from a "hall effect" sensor inside the distributor, which is connected to the ICU via 3 small wires out the side of the distributor body.

This could be ignition related, perhaps your ignition power module is overheating, or your coil is getting old and erratic. or there's some funky wiring around those parts.

This could be fuel delivery related, the fuel pump relay, or the 'radio suppression' relay would be #1 candidates.

 

Thanks for the response Pierce, but now I have more questions...so much to learn

Timing related: Faulty hall sensor is what something I've come across a lot while researching my problem. Reading other people's descriptions of stall issues similar to mine, a new distributor to fix the faulty hall sensor seems to fix their problem. Is it possible to visually inspect this by removing the distributor to see if this is the source of the problem? I've seen a few youtube videos of people replacing their distributor and there is a good amount of corrosion built up on the terminals. If I remove my distributor and see this corrosion, would this be an indicator that it should be replaced?

Ignition: I'm unfamiliar with this one and did not come across it in any of my research so far, I'll look into this more.

Fuel: I pulled my fuel pump relay and someone was kind enough to Sharpe the date it was installed. Since it was last replaced in '08, it could definitely be due for a change and since this part is only $30-ish I don't mind spending that amount and hoping the issue is resolved. The radio suppression relay is also something I'm unfamiliar with and will look into this one more.

 

the radio suppression relay is under the hood, probably near the left fender and power steering reservoir. it powers the fuel injectors.

I've never messed with the distributor on a LH2.2 740 (my 1992 is LH2.4, and doesn't have the hall sensor, instead these use a crank position sensor), so I really don't know what you're going to find inside.

that fuel pump relay, is it a Volvo brand or Stribel, or is it some offbrand? Stribel makes the volvo ones, their logo looks like a small circle with an S inside it thats got )( across it almost like a $ sign. Offbrand relays tend to die a lot faster, the Stribel and Volvo ones generally last 20 years or so.

Ignition, I mean the whole spark system. the Ignition Control Unit (ICU) gets the timing pulses from the hall sensor, and figures out when the spark should fire, and pulses the Ignition Power Module, the power module in turn acts like amplifier and grounds pin 1 of the coil, which generates the high voltage juice that makes the spark plugs spark. pin 1 of the coil is also connected to the tachometer, so the tach dropping to 0 quickly when it dies is quite possibly because the problem is the power module. the power module is a small module probably attached to the inside of the left fender, just forward of the wheel hump, and behind the air filter box.

the ignition power module looks like this...


before replacing these things, I test them in various ways with a multimeter, using some very basic electronics knowlege.

 

I'd first inspect the wiring, especially the wiring going from the Hall sensor alongside the fire wall tracing it into the harness. This being an '87 is pretty prone to wiring insulation disintegration. From experience, this is most likely the cause of your troubles.

 

You might check the ground wire on the negative battery cable (small wire generally attached to the cable end). I had a Toyota pickup that had a similar issue. It would run fine until there was an added electrical load (brake lights, turn signal etc). First I thought it was a fuel issue, then I thought the alternator was going out. Turns out it was just this little wire, which apparently helps the regulator gauge electrical load and tells the alternator to step it up. Without it the alternator goes into a limp mode providing only base power because it can't detect load changes fast enough to respond and keep the motor going.


Since everything seemed to be ok electrical wise (headlights worked, battery was new, truck started fine) it took me sometime to realize it was electrical in nature. The truck acted funny in turns, died at stop signs etc, being a little slow my first thought wasn't the lights used for these things.

 

Thanks everyone for the input. I'll be under the hood all day and post again tonight with a progress update.

Lev, I definitely have some housing that is disintegrated. Would it work to degrease the wires (what products are okay to use as degreaser on electrical?) and wrap them in electrical tape or do they need to be replaced?

 

electrical tape is strictly a temporary solution under the hood of a car.

its possible volvo still has harnesses for that year.

non-turbo LH drive 1987, the main engine harnesses are 1362468 and 1398765
Cable harness engine compartment B230F, B230FT B200ET. Fits: Volvo | VolvoPartsWebstore.com

wow. but the LH2.2 motor harness 1398765 is not available.

 

Update! We had quite a few days of rain so I didn't get to work on the Volvo until today. I found that my alternator belt was loose and when tightened the screw that adjusts belt tension I found it was broken in half. I replaced the screw and now the car runs a lot better, yet the problem still lingers. Prior to tightening the alternator belt, the car would die every block or so, now it dies every mile or two. Hopefully this can give some insight on what's wrong with the old girl.

 

Hy,
i wouls suggest first cleaning the coil contacts the crank/rpm sensor connector & power stage connector before going into expenses.

Nisim

 

a 1987 740 does not HAVE a 'crank/rpm sensor', rather, this LH2.2 car has a hall sensor inside the distributor. crank position sensors were new with 1989 (1990 turbo) LH2.4 cars.

 

This is what I'm worried about. I'm guessing it's my HALL sensor that is failing (though I'm not sure why tightening the alternator belt would make the problem occur less frequently). I've new relays coming in the mail and I've got my fingers crossed this fixes the problem. If not I'll have to take a look in the distributor, but I've had done trouble finding a decent guide on how this is done. If anyone has a video or a link with some detailed pictures I'd appreciate it.

 

Electrical-Ignition

 

It's fixed! Looks like it was a combination of my alternator belt being loose and the power module. Thanks everyone for your time and input. This forum is a fantastic resource and I would have never got my car up and running again without it.