Hello all,

I have an '86 240DL sedan (M46 manual transmission) with 250k miles. Even though it drives generally well for a high-miles car, it has a weird problem that nobody seems to be able to fix. So I'm turning to you Brickboarders for opinions, ideas, or any clues for where to look next. (I'm not a mechanic at all, but I try stay as informed as I can). This may get a bit long, but I beg of you, bear with me if you can.

The problems:

1) (INTERMITTENT - happens about one in twenty times) After driving for a while at highway speeds, then starting up (from 1st gear) after stopping for a red light or stop sign (not turning ignition off, just going to stop and go driving after an hour or so of highway driving), sometimes the car just will not 'go' -- There is a whirring noise (sounds like the pumps are all working), but the engine acts as if it is not getting any gas. Sometimes pumping the gas will get it going again, but in worst cases I have to turn off ignition and crank it back up, almost like 'resetting' the car. Then the car drives away. Sounds electrical, right? Or maybe fuel system? Sometimes the car just hesitates really hard for a half-second, then 'catches' and takes off with a loud chirp of the rear wheels. Very sloppy. People stare at me as if I'm a menace to society or something...

2) I got caught in a snowstorm in western Pennsylvania on Tuesday. After driving at 65+ mph for four hours, I hit the bad weather. When I slowed down to cruise at about 45-50 mph, the car started to 'buck' -- as if the engine was getting fuel for a second, then the fuel system went dry for a half second, then gets fuel for a second, then goes dry, etc. I could not keep a steady 50 mph in either 3rd (3000 rpm) or 4th gear (2200rpm). If I sped up to 65mph (3000rpm in 4th), it would drive along steadily. I was very upset about this and decided to turn back. It seems that once I got back down to sea level, the car settled down and I could drive along at 55 to 65 mph without the bucking. However, it was still bucking and hard hesitating when I stopped at red lights, the whole way home.

3) After driving for a couple of hours at 70 mph in OD, even after going out of overdrive (depressing the OD switch on the shift knob to turn off the "5" dash lamp) the overdrive 'sticks' -- Even if I slow down to less than 50 mph or downshift to 3rd, it seems as if the overdrive is still engaged, i.e. I'll be trying to drive along at 40 mph in 3rd gear, but the revs will be *way* lower than normal, like 1200 rpm. If I come to a complete stop and start up again from 1st gear, usually the OD will finally disengage.

At no time did the car overheat or appear to be losing oil pressure. The engine does not leak or burn oil, or leak radiator fluid.

4) If I do a little 'back road barnstorming' (high revs in low gear around curvey country roads), the car will do its bucking 'hesitate, choke and start off with a screech' dance every once in a while. It's almost as if the stress of higher rpm's (3500 and up) causes the car to freak out.

---

Here is what has been replaced or serviced in the car, in efforts to fix this problem, as well as some other problems.

1) New engine wiring harness installed.

2) New alternator and battery installed.

3) New distributor cap and ignition wires installed.

4) OD ATF drained and refilled with new.

5) OD switch (both the switch on gearshift and the switch on transmission) and solenoid replaced (in-dash relay seems OK).

6) Air filter replaced.

7) Injectors checked, one replaced with rebuilt part.

8) In-tank fuel pre-pump replaced. (This was just done on Wednesday, and did help general driveability -- but did not cure the intermittent hesitation problem).

9) New ECU (supposedly) installed when I purchased the car a year ago.

I've been told that the air mass meter is working fine, and it "just isn't likely to be causing the problem".

I've also been told that the vacuum level in the air and fuel systems seems fine.

I've also been told that the compression reads good in all cylinders, appropriate for a car with a lot of miles, but they all match up pretty well. So there's apparently not a situation where there is one strong cylinder and three weaker ones or anything like that.

I will be replacing the fuel filter, which looks like it may never have been replaced. Could this cause a problem like this? Of course, one mechanic told me this could definitely be the problem, while another one told me 'no way could it be the problem'. Argh.

So please, give me any ideas at all, so I can try to trace down this bizarre problem. I bought the car for $3000 about a year ago and have put another $3500 into it, and I still can't seem to get rid of this incredibly annoying (and possibly dangerous) problem. I've told this story to several mechanics, but they don't seem to believe that I'm telling them what's actually happening.

Thanks to all for your time reading this and any suggestions you may have.

OK, I found your post.

1. On the '86 you should not be hearing the fuel pumps "whirring" while your are driving, or even "hesitating" at a stop. A faint buzzing from the main fuel pump is normal, but you have to be sitting still and quietly to hear that. Aloud main fuel pump could indicate a failing pump, a clogged fuel filter, a malfunctioning in-tank pump, or a bad fuel pressure regulator. Where to start? Fuses. Be sure to install a BUSS (glass) fuse for each pump in place of the ceramic ones. Those can look OK, but be failed.

2. High speed miss usually indicates cracked spark plug. I notice your list of recent parts & services did not include ignition work.

3. Low speed, idle miss indicated a failed spark plug wire or coil wire. BTW, how is the coil?

4. Clogged fuel filter doesn't help. Get the fuel system pressure tested, too. Fuel pressure regulator could be a culprit. Pump relay, as someone mentioned.

5. Any recent throttle body service?

6. What is the idle speed?

7. OD problem could be a relay or bad wire someplace. trace the wires down to the OD solenoid, checking for cuts in the insulation.

To Zee (and anyone else who is following this one):

First, thanks for all the good ideas.

> 1. On the '86 you should not be hearing the fuel pumps

> "whirring" while your are driving, or even

> "hesitating" at a stop. A faint buzzing from the main fuel

> pump is normal, but you have to be sitting still and quietly to hear

> that. Aloud main fuel pump could indicate a failing pump, a clogged

> fuel filter, a malfunctioning in-tank pump, or a bad fuel pressure

> regulator. Where to start? Fuses. Be sure to install a BUSS (glass)

> fuse for each pump in place of the ceramic ones. Those can look OK,

> but be failed.

The in-tank pre-pump was just replaced. The fuel pressure regulator tested OK, but who knows? Quite a few people have been suggesting that the main fuel pump may be intermittent, so I'll have that looked at more closely. But each time I ask a mechanic to check the fuel pump they always say it's OK. The fuel pressure regulator was looked at about six months ago, but I'm not sure I trust the guys who did the checking (they sold me a junkyard pull air mass meter, which I later found out is a really dumb idea. That, and the original AMM seems to be fine, so I had the "new" part pulled and the original put back in.)

I'll also check the fuses tomorrow (it's going to be reasonably warm out, so this will be easy)... What should I be looking for? Blown fuses? I have a Haynes manual which has a chart of the fuses and their functions. I can follow that for clues...

> 2. High speed miss usually indicates cracked spark plug. I notice

> your list of recent parts & services did not include ignition

> work.

Ignition wires were just replaced about two months ago. Had new ignition wires when I bought the car about a year ago, so I don't see why I needed new ignition wires again. Spark plugs were also replaced two months ago. Ignition system was fixed up about six months ago, when I had the rebuilt injector and new injector rail put in.

> 3. Low speed, idle miss indicated a failed spark plug wire or coil

> wire. BTW, how is the coil?

Good question, I'll have it checked again. I think it was replaced when the engine wiring harness was replaced, but I'm not positively sure on that. I'll look on the receipt.

> 4. Clogged fuel filter doesn't help. Get the fuel system pressure

> tested, too. Fuel pressure regulator could be a culprit. Pump relay,

> as someone mentioned.

Fuel pressure was just tested to be OK, but not after high revs I'm sure. Is the pump relay for the in-tank pump the same as the one for the main fuel pump? I can't seem to find that in the Haynes manual (but I'll be looking again now that you've mentioned it...)

I'm going to have the fuel filter replaced tomorrow, just to be safe.

> 5. Any recent throttle body service?

Yeah, it was cleaned back when the injector was replaced. I've been looking for that receipt...

> 6. What is the idle speed?

About 700 rpm when cold, going up to 1000-1100 rpm when fully warmed up. Idle is slightly lower with AC on.

> 7. OD problem could be a relay or bad wire someplace. trace the wires

> down to the OD solenoid, checking for cuts in the insulation.

I might wait for warmer weather and follow this through myself. I can live without using the OD, but I can't live with this lurching/bucking/hesitation thing.

One more thought... The shop that replaced the engine wiring harness (Integrated Automotive Services in Easton) managed to break the cruise control when they did the rewiring work. When I asked them about it they said it was an easy fix, just a hose not attached in the right place. I have no info about this rather rare cruise control assembly, so I can't tell if it's hooked up right or not. This couldn't be causing these problems could it? Maybe your Bentley manual has some info?

Thanks again!

BE sure to check the 25amp blade fuse located in the engine compartment.

It's on the drivers side fender and is the main fuse for the fuel pump-ignition. It has a red wire running directly to the positive battery terminal. pull it and see if there is any corosion .. it's cheap so replace it anyway.

this fuse due to it's location can get wet - also check the holder for corrosion as well as the post on the positive battery terminal. clean the connections. IPD even sells a special waterproof holder for this fuse as it is infamous for causing problems in LH injected Volvos. Its location is one of those Volvo engineering mistakes that were never corrected by Volvo.

this fuse and bad contact at the holder can cause many strange problems but is often overlooked. I did not see any mention that this fuse was ever checked in any of your posts.

Re: the ignition wires. I had a missing bucking problem on my 87 that I could not figure out - I went so far as to replace the Hall Sensor in the distributor. But the problem turned out to be a bad ignition wire...even though the set was new, just a few months old. I found it by doing what Don Foster reccommended- a midnight viewing. You might try this to eliminate a short it the ignition system. In the dark of night or in a dark place while the car is acting poorly. open the hood and (it needs to be very dark) look at the engine. any electrical "leaks" will be seen as blue flashes. On mine I saw blue arcing along the bad sparkplug wire. If the Hall sensor in the distributor is arcing you should see blue around the distributor.

Thanks to everyone for the information and suggestions. I'll be printing them all out so I can check back in the future...

> BE sure to check the 25amp blade fuse located in the engine

> compartment.

This was just replaced for the second time. Seems that this is a favorite 'cheap insurance' replacement -- but how many times do I need a new one?

> Re: the ignition wires. I had a missing bucking problem on my 87 that

> I could not figure out - I went so far as to replace the Hall Sensor

> in the distributor. But the problem turned out to be a bad ignition

> wire...even though the set was new, just a few months old. I found it

> by doing what Don Foster reccommended- a midnight viewing. You might

> try this to eliminate a short it the ignition system. In the dark of

> night or in a dark place while the car is acting poorly. open the

> hood and (it needs to be very dark) look at the engine. any

> electrical "leaks" will be seen as blue flashes. On mine I

> saw blue arcing along the bad sparkplug wire. If the Hall sensor in

> the distributor is arcing you should see blue around the distributor.

That is a great trick! I'll try that in a few hours. New ignition wires were just fitted in September, replacing a set that had been installed in Dec, '99. I don't think this is a problem, but the ignition coil does look old... Could a problem coil cause arcing? I'm a little suspicious of the electrical system since the engine wiring harness shorted out in April...

Thanks again!

Ron Gonzalez

1. The hose for the cruise control was jsut asked about on the RWD board. Look down past the throttle body to the ear of the engine block. there is a vacuum hose there. Maybe that is what IAS means.

2. On the fuses, about all you can do there is make sure the fuses are good and maybe clean up the copper contacts with a nylon scrub pad. Switch to glass tube fuses, like BUSS.

3. Idle is to be about 700 cold or hot. About 950 with AC. suspect your Idle Control Valve dirty of faulty. Dirty can be removed and cleaned. Faulty, no, need to replace. Probably not your problem, though.

4. The fuel pump relay is located on the inside of the firewall on the passenger side, just about where the rider's right foot would point. Just inboard of the ECU. White plastic box. Solid state connections can weaken and crack. Can be resoldered. New is about $40-50

OK, here's the latest:

I had the fuel filter replaced and... it looks like the car had the ORIGINAL fuel filter still on it! At least the old filter said "VOLVO", not BOSCH as I would have expected. The old fuel filter was also badly corroded and dented. Not a pretty sight. With the new filter I've already noticed a big improvement in idle steadiness and drivability at low speeds/rpm's (no more near-stalling). Could it be that I was driving around with a fuel filter that had seen 250,000 miles worth of use??

The fuel pump is also really dirty and rusty on the outside. I would not be at all surprised if it chokes intermittently after a bit of high speed or high rev driving. It tests fine though, so I won't replace it yet (I've just spent $1000 on the car and my money supply is completely tapped out). But I did notice RPS has a sale on the Bosch pump ($139), so I might just replace it as a preventative measure.

Zee wrote:

> 1. The hose for the cruise control was jsut asked about on the RWD

> board. Look down past the throttle body to the rear of the engine

> block. there is a vacuum hose there. Maybe that is what IAS means.

I'll check and see if I can find that. Would I find info on the cruise control in the Bentley manual?

> 2. On the fuses, about all you can do there is make sure the fuses

> are good and maybe clean up the copper contacts with a nylon scrub

> pad. Switch to glass tube fuses, like BUSS.

I pulled out the fuses and checked them with a DVM, all tested fine (no resistance). IAS told me they had cleaned the fusebox when they sold me the car last year. It does look reasonably clean.

> 3. Idle is to be about 700 cold or hot. About 950 with AC. suspect

> your Idle Control Valve dirty of faulty. Dirty can be removed and

> cleaned. Faulty, no, need to replace. Probably not your problem,

> though.

Hmmm, interesting... On my car, idle goes *down* when I turn on the AC. I was mistaken yesterday about the idle speeds though. When I first start up the car, idle is about 700 rpm, 900 or so when warmed up. Once warm, always is at 900 in all kinds of weather; definitely is lower rpms at cold startup. But I definitely see the idle go down when I turn on the AC. Anything noteworthy about that? Maybe my AC system is worn out or drawing too much current?

> 4. The fuel pump relay is located on the inside of the firewall on

> the passenger side, just about where the rider's right foot would

> point. Just inboard of the ECU. White plastic box. Solid state

> connections can weaken and crack. Can be resoldered. New is about

> $40-50

Looking through my service records I see that the fuel pump relay was just replaced along with the in-tank fuel pump, this past Monday (at Dougherty's in West Chester, PA).

I've found that the choking/lurching/hesitation thing is worst when I go out on the highway immediately after a cold start, and especially in humid and/or cold weather. I drive 20 highway miles every afternoon from work, so next week will be the test.

Assuming the ignition wires are fine (I'll check for arcing tonight), if the problem continues that will leave three likely suspects for me to look at: the main (external) fuel pump, Idle Control Valve, and the ignition coil. How's that sound to you?

Thanks again for all the valuable information. BrickBoard rules!

Ron Gonzalez

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Ron:

One thing I would suggest (even though you claim not to be much of a mechanic) is to buy a "Bentley's" manual. The Haynes and Clymer are okay for minor tune-up work, but to really get an idea of how these systems work, you need a Bentley's. The actual title is "Volvo 240 Service Manual" and is published by Robert Bentley, Inc. You can search MySimon or any other book search by its ISBN#. This book's ISBN is 0-8376-0285-8.

I'd check all of the vacume hoses, and redo those is nessesary, as well the catalytic converter, if it's stopped up can cuase problems.

check your constent idle motor if is happen during idle. Also you may need to have the throttle body cleaned.

Josh,

What problems might I be likely to see if my catalytic converter was blocked up?

Thanks,

Ron G

Ron:

Check your fuel pump RELAY and main fuel pump. I would suspect the relay first (costs about $40 and is easy to replace). the main pump lasts about 10 years or so, if Bosch; 5 years if aftermarket. Buena suerte,

Genaro..

Always change the fuel filter. It is amazing what a new fuel filter can do to improve the performance of any car. MR