The PO reported a long standing issue with the car suddenly quitting and today the car acted up missing/loss of power/and would have stalled without extra gas peddle. Then after maybe 2 minutes it cleared up and ran fine.

I drove three errands of maybe 3-4miles afterward and each leg the car ran fine.
The PO said it quit/ran ragged mostly when it was hot. This sounds like a fuel issue to me, but today was cool out 65F and it acted up before warming up..
Are there two issues here: Vapor lock and a separate fuel pump problem?

This same problem was last addressed by the PO at a garage in Boston about 6 weeks ago. The complaint: "Dies while driving"
The shop replaced vacuum hoses ($15) and "Idle speed motor (used)" ($125.00)
and changed the oil. $686.50 T (I got whiplash looking at this garage's bills) Did that guy mean Fuel Pressure regulator?
Looking at the 900 "Fuel FAQ" I wonder if the problem is in the gas tank
plumbing/ filter/ pre-pump? I can't tell if there's a pre-pump or not
and maybe have to call Volvo with my VIN # for this info?
It had a new fuel filter installed recently, and a bottle of injector cleaner
into a full tank today.

The fuel controller (mistakenly called a relay) is another prime suspect for funky fuel starvation. Usually they gag with heat and start working when they cool off. My failure started before the car warmed up and cleared up
afterwards? Are there different fuel controllers for Turbo and NA?
I have an old controller # 3523608 that might be right to swap in and see what happens ?

Am I on the right track thinking fuel on this issue?

Bill

Hi Bill,

For your rough running diagnosis, you have checked for DTC fault codes?

https://www.brickboard.com/FAQ/700-900/EngineOBDCodes.htm

As spook says to treat bonded low volt electrical connections using DeoxIT-D.

The 700 and 900 series has that fuse and replay board or platform hidden under the center console behind the ashtray on 700 and 900.

As spook points out, the aged electrical connector can form corrosion and that resistance the corrosion presents.

Read John Sargent's comments here and in posts you can search for on the topic:

https://www.brickboard.com/FAQ/700-900/ElectricalCircuitsRelays.htm#Relay_and_Fuse_Panel_Removal

Glad you got the Haynes manual. Hopefully shows process diagrams on your model year.

Did the Mitchell Service diagrams help? Not the electrical system process diagrams, yet pretty okay:
http://www.v8volvo.se/mekartips/volvo/

And you need to perform some suspension work also? Do you have the "live" rear axle or the independent rear suspension (IRS). If not already, bushings on either rear axle may need replacement. On IRS, there are seals, U-joint boot covers and bearings and splined shafts on the axle that would appreciate a good cleaning and grease repack.

Else, if an idler armor steering link is bad, replace in pairs. I'll imagine you have read through the FAQ.

Hope that helps and happy Sat-Your-Day!!!

Buttermilk Volvo

--
Beh.

Buttermilk Volvo! That's the Volvo dealership at Lake Woe-Be-Gone, now I know where you live and/or work.

Today I found complete 940 wiring diagrams for 1994 & 1995. It's interesting that the 94 wiring diagram TP3904202 includes mods up to Sep 1993. The first thing I did was look up the power amplifier and rehab the thermal grease and used the official Volvo toolkit (torx driver) to get it off the fender. Thus saving $600 over dealer service rates. Today is one fine Sat-your-day.
I'll give anyone the link via private email only, since Geeley and or Google will take down the site. You can get a disposable email account, something mysterious, use the part number for the Volvo Fallopian tube: (898151@gmail.com) and sign with your usual signature so I know it's you.

The engine has run fine since replacing the fuel pump relay, not one hiccup.
(knock on wood)

The inspection tech said sloppy tie rod end on driver side- I put a tie rod in and noticed play at the rack- if the passenger side is down and the driver side is up can that slop be due to the pass. tie rod rod end being sloppy?

How big a deal is it to repair a rack if that's the problem? inner ball joints? I see sway bar and end link bushings that are worn and a YT video about rehabbing control arm bushings. Do I want poly bushings?

Happy motoring, Bill

As Spook alluded to, do not ignore the ignition side. You may well have multiple issues going on with your car, but the particular symptoms you describe in the above post of starting okay but with occasional missing/hesitation and needing to push the gas pedal when cold then smoothing out and running okay when warm are indicative to me of electrical and spark issues, not necessarily fuel starvation, although that's still a possible issue for you.

If it was the power stage ignition amplifier failing (thermal paste failure) or the RPM sensor (on the bell housing, you do not have a Hall sensor on your LH 2.4 with EZK-116) or even the fuel pump relay (you should have the small green/blue Hella cube relay in your 940T) then things generally get worse as the engine warms, not better.

IMO for the particular problem you describe above, you should be looking at, in order of simplicity and likelihood:
o Fouled or badly worn plugs (forget platinum or multi-electrode, stick with quality OEM style copper plugs).
o Loose fitting or improperly seated ignition wires on the spark plugs or loose caps on the threaded plug ends (this has in the past given me the exact same symptoms in my 940T as you describe).
o Loose fitting or improperly seated ignition wires on the distributor or coil (especially the lower wire on the distributor from the coil).
o Ignition wires failing or dirty (they don't last forever, also oily residue on the spark plug or boot may be from a leaking valve cover gasket or oil filler cap).
o Distributor cap/rotor worn, dirty, moisture, cracked (often ignored on the 740s/940s as the rear mounted distributor is a bit awkward to get to and not overly cheap to replace, choose Genuine Volvo/Bosch).
o Worn distributor shaft seal/bushing (evidence of oily residue inside the distibutor cap)
o Failing power stage ignition amplifier (left front fender)
o Failing injector (radio suppression) relay (right front fender)
o Leaking injector seals or sticky injectors (uncommon with these pulsed injectors on the fuel rail)

Being a newly acquired car with unresolved issues from the PO, as long as you're checking and cleaning up the ignition side then do some preventive maintenance like refreshing the thermal paste under the ignition power stage and carefully inspect the RPM sensor cable (signs of worn or split sheathing, especially down by the sensor itelf). To prevent moisture from becoming an issue, apply dielectric silicone grease (spark plug grease) as a waterproofing sealent to all ignition wire boots and pack the female socket side of the electrical connector on the power stage -you can do the same on the fuel/air side electrical connectors such as the AMM, IAC, TPS, just not the O2 sensor connector. If you do a decent job of waterproofing the electricals you should be able to lightly wash and rinse the engine and under the hood and restart without a hiccup, as both my engines do. Keeping oil and dirt off rubber, plastics and wiring will greatly increase their longevity.

Do some more poking around in the FAQ. There are a number of areas and many tips in the FAQ that address the kinds of issues you are having. Remember that you do not have Rex-Regina, you have LH 2.4 in your B230FT (all 1990-on turbos used LH 2.4).
--
Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now

Hi Dave,

What a terrific response!
There's so many items to respond to here.

The fuel relay was not a green/blue Hella- It was a white Stribel (made in Hungary) dated 10-12-2008. I replaced with a 740 relay same part # 898151
and the car has run great since.

I'm at a disadvantage with no Volvo 940 wiring diagram, but do have the 940 Haynes manual on the way.

I have power washed the engine twice, since there was an oil leak at the front of the engine reported in some of the Boston based service records. I see no sign of any leak from the valve cover at the front of the engine yet, and suspect that the PO simply messed up when adding oil, and the Boston garage used that to fabricate a big bill. (I can email you the three bills if you want, you'll probably get angry looking at them)

I have not looked at ignition yet.
Is that the power stage mounted down low under the driver side headlight?
Is the rehab of the heat sink compound obvious?
Then I can do it tomorrow to be pro-active since it's likely the intermittent
failure when hot.

Today I replaced the drivers side tie rod end. There was slop afterwards noticed at the rack, when holding the wheel at 9 and 3 O'clock. I don't know the details of the rack. Can it be a bad tie rod end on the other side?

Do any tie rod ends have Zerk fittings now? The manufacturers get worse and worse with time it seems. (That's why I like old Bricks)

I studied the FAQ and the 740 Haynes suspension info and talked to IPD today and have questions galore.

Is there an easy way to diagnose a bad tie rod end vs. a bad control arm ball joint, and do worn bushings add to the misery here? The FAQ doesn't discuss ways to diagnose what has failed in the suspension. It's focused on replacing individual items. I see some bushings are junk (sway bar and end link) but there's others that probably need replacement while I'm in there.
(IPD has a bushing kit: out of stock) What do I want for bushings to be proactive?

Cheers, Bill

Fcp sells relay s pretty cheap.Have you replaced the air filter.I just did on my 945 ^& wasnt even dirty or clogged looking & a new one solved most of my hesitation.

Regarding your intermittent stalling, loss of power and poor running. I had similar running problems with my '92 940T and found replacing the 2 wire fuel injection temp sensor solved it completely. - Dave

he should try renting a fuel pressure gauge & seeing if its up to snuf,,or snuff The shrader valve should be near the filter/fuel line under drivers seat,
I just solved the hard starting problem w my 940 non turbo by taking the throttle body off cleaning it theorughly &shooting more tb cleaner in the throat. I turn the key & it Jumps to life><>>Q!!!!

The last mechanic used by the prior owner "PO" was a bandit, and did not solve the
issue or perhaps issues of erratic fuel delivery and maybe vapor lock.

The car started acting funky with rough idle and RPM's unstable, then seemed starved for fuel. I changed the fuel pump relay with a spare and it's behaved
OK since. I ordered a new one, and it's in the glove box for when I have the
fuse block out next. I don't trust old fuel pump relays, and have also had a new KAE 850 fuel controller crap out quickly with quirky intermittent fuel problems.

I sent you mail via Brickboard about the shifter knob with no response, is your profile up to date with a valid email address?

Bill

Hi Dave,

Thanks for the heads up about the Temp sensor.
Did the bad one measure different with an ohmmeter.
How much grief did you have finding the fault?
Is there a thread somewhere?

I'm still hunting down the Volvo wiring diagram so I can
work on the wiring. I'm in left field with what I've found so far.

Thanks, Bill

Replace your ignition module.....You heat sink paste is old between the mount and unit and not transferring the heat off the electronics. Causes intermediate failure when hot. The other cause of your problem could be the hall sensor inside the distributor. Same problem when hot. $50 for a complete new distributor.

Hi Paul,

Thanks for the suggestions.
The engine ran ratty when first started then it behaved worse almost stalling.
Then after a few minutes of gagging it cleared up and ran normally.
This is one unresolved condition described by the PO. I swapped out the fuel
relay and it's behaved for a week. There's a new one that just arrived today that I'll put in soon.

It may be that there's other intermittent bugs to find related to heat.

Where is the ignition module, and does it dissemble to rehab the heat compound
on the heat sink? Is that the box down low under the drivers headlight?

(I'm still searching for the wiring diagram that makes this stuff easier with fault tracing and component locations, etc.)

Bill

Dear B.B.

Hope you're well and stay so. The ignition control module (ICM) - made by Bosch - has a black body and a flat gray cap. It is mounted on an aluminum base, secured by two screws to the upper portion of the inner fender wall.

The ICM is located just behind the headlight. On non-turbo models it is to the rear of the driver's side headlight. On turbo-equipped engines, the ICM is to the rear of the passenger-side headlight.

The heat sink paste should go between the ICM and the aluminum base.

Hope this helps.

Yours faithfully,

Spook

Dear B.B.,

Hope you're well. For a car nearly 30 years old, intermittency likely results from worn-out relays and/or corroded electrical connections of those relays. Sometimes an invisibly-thin layer of corrosion - a few molecules thick - suffices to disrupt smooth operation. When connectors are corroded, changes in heat and ambient humidity suffice to disrupt the flow of power.

As your car has a turbo, it has Bosch fuel supply and management. So, there's an in-tank pre-pump and a main fuel pump, mounted on the under-body, approximately under the driver's seat. These pumps are pretty robust, so should not be an issue, unless the car has lived in the salt-belt or near an ocean. If so, then the main pump's electrical connections should be inspected.

Thus, I'd replace: (a) the fuel pump relay (white rectangular unit, mounted on the main relay panel behind the front, center console's ashtray; (b) the fuel injection relay (also known as the radio interference suppression relay) dark-brown, mounted in the engine bay, on the inner fender wall, to the rear of the driver's headlight; (c) the ignition power stage (flat, with a gray cap, engine bay, inner fender wall, to the rear of the passenger headlight).

If these steps do not end the problem, then look at: (a) the distributor cap/rotor and (b) the ignition coil, a cylindrical device (black or aluminum casing) mounted on a strut tower. The distributor cap/rotor should not be - and likely are not - factory-original. But if moisture gets into the distributor cap, rough-running would not be surprising.

Use an aerosol corrosion-remover, e.g., Deoxit, to clean the wiring harness connectors.

Key point: the parts that I suggest be replaced - if factory-original - are going to tail sometime soon because they're at or near the end of their service life. Thus, the replacement cost is going to have to be met sometime soon. Replacing them - and cleaning the wiring harness connectors - ensures smooth operation for a long time.

Hope this helps.

Yours faithfully,

Spook

Hi Spook,

I was wrong about the 940 fuel relay 2-31. The 850 does the job of powering
the fuel pump with triacs and I think of it more as a power supply than a relay. Volvo calls it a fuel pump controller.

Now I find the 940 fuel pump relay is a pair of relays in one box.
I think the computer cycles power to vary the output of the pump to meet engine demand and not overdrive the pump to shorten its life. So 2-31 the fuel relay gets beat up from heavy use. It probably needs to be changed as a function of miles just like a T-belt. A new KAE fuel controller in the 850 crapped out with less than 2K miles! So maybe the controller is designed to be robust with a healthy fuel pump and heats up if the fuel pump gets worn?

I wish we could gab on private email or the phone. Some of the Brickboard heavy hitters here are bashful. Maybe they're in the witness protection program and have gangsters after them? :-)

Anyway, Thanks for the nice write-up about the 940 shifter knob, that helped me out today. Keep up the great work! Maybe put a disposable email link up in your profile?

Best regards, Bill

Dear Bill,

Hope you're well and stay so. The 850 has little - if anything at all - in common with the 940.

I'm not in the least worried about anyone coming after me. I strive to treat everyone with courtesy.

Courtesy is like engine oil: a whole lot isn't needed and one can even be down a half-pint without major problemd. But a lack of a quart of courtesy is a problem.

Hope this helps.

Yours faithfully,

Spook

Thanks spook,

Today i wrestled the fuse block out and stuck in another fuel controller
It had the same part number as the one removed. Then a short test ride to a locksmith got two Volvo keys for $10...Woo Hooo! Try that with a new car.
The car hasn't acted up. Maybe the infamous fuel controller is the villain here.
I'll order a new one later this evening. With my 850 I changed the main fuel relay (AKA RSR) and the fuel pump controller (AKA mistakenly Fuel pump relay)
With new KAE parts. after a short time the KAE fuel pump controller started acting bizarre, quitting then after a wait, working etc.. It was a rubbish part. I got the more expensive Stribel (Made in Hungary) and it was better.


For some reason the fuse block wants to hang up before it locks into it's
white plastic nest, and it doesn't like coming out once its in. I can't see any reason for it. The gas gauge quit again after the wrestling match with the fuse block. I used a very thin film of dielectric silicone on the connectors
and it seems happier. There might be a solder connection I missed under the small tin box near the gas gauge. If it keeps quitting I'll put jumper wires.

Do you have part nrs for the small wedge lamps for the instrument cluster?
Are there two different sizes? This is a Yazaki cluster. I have an old VDO and the lamps are different

The self locking drivers door started to behave after forming the bent upper link
that wanted to settle outside the door with a little amount of pressure.
I formed it to settle on the inside of the door and suddenly the door doesn't self
lock! It remains to be seen if it stays fixed. Probably it will lock as soon as I don't have my keys.

I have some high power LEDs for backup lights and Ach I suppose you take two bolts out to get the whole assembly where you can grab and twist the lamp holders? My hands are too big to safely reach into the back through that small
opening without removing all the skin on my knuckles. Its a wagon
Now I'm looking for a donor car at some local salvage yard. The shifter lever (auto tranny) is broken up top. How big a deal to replace.

I'm still searching for a 93 940 Volvo wiring diagram Greenbook.

Has anyone tried LED headlight conversion in 940s? Some dealers claim to have
them online?

All the best, Bill

Dear B.B.,

Hope you're well and stay so. The speedometer bulb - of which four suffice - is #989794. It should cost about $3 at a U.S.-based Volvo dealer.

Each of the rear light clusters on a wagon is secured with three 10mm nuts: two at the bottom and one at the top. The lower two nuts are accessed by removing the floor panels just below the light cluster openings. A 10mm deep socket - on a 6" extension - will allow the nuts to be removed. You'll see two, one-inch diameter holes in the sheet metal. Insert the socket and extension through those holes.

While you have the cluster in hand, it is a good idea to clean to contacts on the cluster and on the wiring harness, to remove any oxidation. Again, an oxidation layer can be so thin - a few molecules - that it is invisible. That may be enough to trigger the bulb burn-out warning light.

Hope this helps.

Yours faithfully,

Spook

Hi Spook,

Thanks for helping me sort out the bugs in my first 940.

the Yazaki warning (idiot) lights have a small wedge lamp inserted into the little plastic holder. Do you have info on those bulbs?

Thanks, Bill

Dear B.B.,

Hope you're well and stay. Volvo VADIS -a superseded dealer parts/service database - shows the instrument cluster warning light bulb is #942327. Check with a Volvo dealer to see if this part number is still valid. I think this bulb has been used in many newer models, so should still be available from Volvo. Other parts suppliers, e.g., www.fcpgroton.com may also supply it.

Hope this helps.

Yours faithfully,

Spook