'91 940 No Spark, No Fuel

volvoaddict007 · Post by **volvoaddict007** » 22 Aug 2007, 07:25

Turns out the '90 760 Wagon's motor has been replaced with a '91 940 motor as opposed to an '85 740 motor .

This car which has been totally reliable since purchasing 5000 miles ago decided one day to turn over as usual but will not start.

The car does have gas.

Only neg mV at Fuel pump when first turning on ignition. Yes, I unhook battery to reset and then test. Fuses are fine. There is continuity but no voltage at fuse box for both fuel pumps.

After resetting battery only, I do hear what sounds like a fuel pump for approx 4 seconds when I put my ear against the armrest on the center console.

No voltage at fuel relay.

No voltage at fuel injectors ( Neg. lead grounded , pos. in each side of injector )

No voltage at coil.

The ECM ( unknown mileage ) has been swapped w/ a used ECM ( w/ an undated VOLVO service sticker ) with identical #s. It is not known that the replacement ECM is good.

The ignition switch has been known to catch and not allow me to turn the key past full off.

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Is there a way to bench test the ECM w/ only a voltmeter? If not could a regular or Volvo specialist check it out of the car?

What else in order should I check.

I don't have a wiring diagram and if I did it would probably look foreign to me as electrical is one of my many weaknesses.

wojeepster · Post by **wojeepster** » 22 Aug 2007, 20:07

get a volvo wiring dia gram for your car here:\

https://www.volvotechinfo.com/index.cfm ... =home.main

then get tracy martins
"how to diagnose and repair automobile electrical systems"

light years ahead of every other auto elec book I have read. In your case follow 12v each leg in circuit until you find prob.

CarVolvo · Post by **CarVolvo** » 22 Aug 2007, 23:17

if you dont have any voltage on the relay then check the fuse on the firewall... its a spade bit. Take the unit out and sand the part it clips in to make sure there isnt any corrosion or build up.

Also remove the cable attached to the battery that runs to the fuse. They are known to buld up corrossion too..so sand it and make sure that is operating properly and your getting voltage to the relay.

wojeepster · Post by **wojeepster** » 23 Aug 2007, 15:31

don't hold me to it but I think these cars check for spark and it there is none then you get no fuel. so you may only have one problem here. do you have voltage at the coil with the key on?

volvoaddict007 · Post by **volvoaddict007** » 23 Aug 2007, 20:02

Thanks for the quick replys,

Wojeepster , I located the Tracy Martins book in town and am picking it up after I post this. Looks like Borders has a hard time keeping it in stock but one of thier stores in K.C. is holding one. ( $25 or Amazon $13-17 but you have to wait or pay like $20 for next day )

Looks like the wiring manual will take some time to get here.

TRIVIA ALERT!!!

I thought that the second digit of 3-digit model #s designated # of cylinders which is usually the case on later years. ( 240 forward )

Therefore I assumed that this car previously had a 6, therefore different wiring harnesses , ECU etc. Volvo specialist said the 760s came with 4s AND 6s. Finally got a hold of the previous owner and YES, this car did have the 4 originally. Only the RELAY FOR THE FUEL INJECTORS ( see below ) and the radio resistor jiggamabob ? have been changed. That was really bugging me, contemplating 2 different wiring systems.

So hey CarVolvo,

Is the firewall the entire inner walls of the engine compartment or is it just the panel between engine and interior?

I don't know what a spade bit is

While I was digging around I found a SMALL SQUARE BLACK RELAY with homegrown connectors (no connector housing) laying against the strut housing/wall. It had a 2mm section of bare wire that looked like it could have grounded on a hex screw. I'm guessing this is for the FUEL INJECTORS.

It was under some other wires and I missed it before.

Well I'm thinkin' EUREKA!!!

The car still won't start...

I check the #30 fuse ( fuel injectors, fuel pump ) for continuity even though IT LOOKS GOOD.

IT'S A BAD FUSE!!!

...

Runnin' like a sewing machine.

In the meantime during my junkyard searches, I found a perfect tail lense ( my left one was severely faded ) glove box liner, REAL wood dash inserts, middle break light cover, spare ECU and fuel relay, and rear speaker for $129.

I also got great info from you guys who just want to help the poor and mechanically challenged like myself. YOU'RE THE BOMB!!!

Oh yea, I also discovered a short at the middle brake light( It was missing the cover and connector had bent over and grounded. I had no brake lights !).

I noticed that Haynes only has a repair manual for '82-'88 760s ( not '89-'90). Should I get it or is there something better?

Thanks again,

va007

Wojeepster, My understanding is that yes, the ECU checks for both and won't give one if the other isn't present...CarVolvo? Yes, I had checked for voltage at the coil... zippo

Does anyone know of other later models that has the second digit anomoly

Post by **billofdurham** » 24 Aug 2007, 12:07

780.

It came with a straight 4 turbo or a V6 engine.

The V6 was the PVR (Peugeot, Volvo, Renault) 'collaboration' which should have been spelt 'abomination' as it was so unreliable.

460 and 480.

They had a straight 4 turbo or naturally aspirated engine but didn't get to the US.

360.

It had a straight 4 non turbo and again it didn't get to the US

Bill.

wojeepster · Post by **wojeepster** » 24 Aug 2007, 15:25

I am happy to hear thzt you fixed it! Whenever I am able to fix something it always seems like the heavens open up and naked angels are singing! I guess because of this I drive cars that no one else can waiting around for something to go wrong. When something does it it an easter egg hunt! You might also find this site useful when you need something (I bought two working air mass sensors for $20 each)

www.car-part.com

volvoaddict007 · Post by **volvoaddict007** » 24 Aug 2007, 20:50

Ah, So good to hear from the Master of Volvo trivia...Bill of Durham.

I knew about the 780 ( I owned a 4 for 2 days ) but thought I would throw out some bait.

Now these other autos of historical interest that you speak of. Is there a website that I can take a looky loo. Did they look like certain model Volvos we were getting here? What years were they?

I saw an Amphibicar today in real life. Now that's a pretty famous car. I was told it was German. I thought they were American.

With all the rich folk around nowadays, you'd think there would be a real market for that sort of thing. In the state I live in these cars don't need a license plate because the vessel # supersedes it.

Thank You Bill,

va007

volvoaddict007 · Post by **volvoaddict007** » 24 Aug 2007, 21:51

wojeepster wrote:I am happy to hear thzt you fixed it! Whenever I am able to fix something it always seems like the heavens open up and naked angels are singing! I guess because of this I drive cars that no one else can waiting around for something to go wrong. When something does it it an easter egg hunt! You might also find this site useful when you need something (I bought two working air mass sensors for $20 each)

www.car-part.com

wojeepster,

Your post was so hilarious, I was starting to well up. I can relate! Man, when that car started up I was so friggin happy. It was sitting there for a week and it's my work vehicle. I had recently dubbed it Mr. D for DEPENDABLE. The problem as you read was not a fault of the original engineering, so the name still applies!

Yet, all the great things that happened in the process. Who knows, I could have had an accident with no brake lights. And if you saw how the wire was bare in that one little area. It took 4 years of vibration to get that way. I guess the guy who put this car together either figured that the relay laying down loose wouldn't hurt it or he just overlooked it. I found a small screw in my parts bins and a hole was already there ( on the relay as well as a bracket on the strut housing/wall ) to just zip it into.

Anyway, I'm dealing with another perplexing problem w/ the 850 under "Weird 850 Electrical Problem". But it's not one that keeps the car from running. It is actually pretty tantalizing. Like the Easter eggs!

Thanks again for the recommendations,

va007

P.S. I'm curious what car(s) you own. I have 2 pretty amazing Jeep stories for you... and one involves a rental.

Post by **billofdurham** » 25 Aug 2007, 12:38

the Master of Volvo trivia...Bill of Durham

Is there a quiz about this and what is the prize?

Try this link to see some pictures of the other Volvos:

http://www.volvogallery.org.uk/

The 3 series Volvo was made in Holland and was a follow-on to the Daf 33/44/55/66 which would definitely not have been sold in the US. It did not share the Daf drive system which was a variable gearbox using big rubber bands, but its gearbox was mounted just ahead of the rear axle.

The 360 was made from 1980 - 1991, the 460 from 1988 - 1997 and the 480 from 1986 - 1997.

Bill.