Hello all,

Recent purchase for parts, decided to get it running & keep. 1987 US gasoline 240 5-speed (m47). Friend got it running briefly on starter fluid, so replaced pumps & fuel relay, but still wouldn't start normally. He then noticed wiring was a mess (bio-degradeable, right?) so I'm troubleshooting it. Fact that it ran on fluid leads me to think that while I do have some wiring / electrical issues, they aren't actually terminal.

Anyway, I searched for my issue here and found this thread . . .

https://volvoforums.com/forum/volvo-...l-pumps-81734/

. . . which is quite helpful. I've done a similar jumper (I thought 4 & 6) to hear the main pump humming. Will '94 & '97 US car be the same as far as jumpers? I don't think I got the in-tank pump going.

Back to wiring; in other threads I noticed reference to a 25A fuse near drivers' fender under the hood. I cannot find mine! Photo attached, and I suspect that the PO removed it, and it would normally sit where the red battery wires are "spliced" together with black tape (appx. center of first photo, img_2844.) Is my assumption correct? Or is it actually on the fender? I found connectors there, but no large blade fuse, or any fuse for that matter!

I have also "insulated" all the degrading wire that I could find, at the grey connector behind the motor, as well as at back of engine bay on passenger side (other photos) - I figured any shorts there would be creating a nightmare.

My next steps are to try the jumpers suggested in the other thread & try to hear both pumps. Then actually check that fuel is getting to injectors when pumps are running? And if not, track backwards and see where I DO have fuel moving. Does that sound basically reasonable?

Also, is there a way (jumpers, listening, etc.) to check the fuel pump relay?

And finally, is that referenced 25A fuse required? And what does purpose does it serve? I know there is an upgraded connector that I can order, & I will, but I'm simply not sure where it is meant to go - and what other damage might have been caused if it has been removed.

And IF I can get this wagon running, I would replace the wiring that I have simply taped up to "insulate" but it's tough to commit to that until I know I at least have a viable project.

Appreciate the insight of the group. Thanks!

 

To operate both pumps:

With the key out, jumper the left side of fuse 4 to the left side of fuse 6 to run both pumps.

To operate the in-tank pump:

Remove fuse 4 and with the key out, jumper the right side of fuse 4 to the left side of fuse 6.

The 25A blade fuse is what the whole F.I. system runs through. Pretty foolhardy for someone to have hardwired it. It goes from the battery+ through the fuse into the harness behind the intake. You can get a waterproof 25A holder and re-establish that fuse. For the time being, I would not fuss with that wiring any more unless it is very evident there's a problem. Not all cars suffer the same fate with the bio-wiring, but bending and twisting 25+yr old wiring can cause some problems.

 

Looks to me the fuse is still there. In photo #2 (one showing power steering reservoir) there is a small black case mounted to the fender. Remove the cover of that case to reveal the 25A fuse.

 

Thank you both.

fochs - I'll try the jumpers you note

act1292 - I thought I had removed that cover and saw only junctions underneath there. But I'll look again for sure, it certainly wouldn't be the first time I'd missed something right in front of me.

And no matter what, I'm pulling the electrical tape off the red wire from the battery, I need to satisfy my curiosity as to why it is there.

 

the fuse you jumper to should be labeled 'tank pump' on the fuse cover. the fuse you jumper from is 'clock' or something else thats always powered

it is indeed fuse 4 on a 87. fuse 6 on a 87 is always powered, and is labled 'main pump' but is only used on CIS cars, not USA LH2.2.

 

oh, and your main ground at the battery cable looks AWFUL.

 

Yeah - it looks to me the reason the black tape is on there is because half of the insulation is flaked off. In many of the pics it looks like someone kept patching the wiring harness as wires became bare. Really could use replacement.

 

the scary thing is, if you were to strip back the black sheaths that cover the bulk of the wiring harness, you'd likely find sections that look like..



(thats a mercedes harness, they had the same biodegradable wiring, only it was 1993-1997).

 

Thanks in advance to those who have chimed in with responses - much appreciated. With life, family, weather, etc., my progress has been intermittent & slow.

Have confirmed that fuel pumps are working, fuel relay clicks satisfactorily when key is turned "on", and most importantly, I have physically verified fuel to the rail. What I was NOT getting was any fuel OUT of the injectors. And they have been cleaned.

So now I have tested and found that I am not getting any power at the injectors. Noid light (correct Bosch one) does not flash when engine turns over and with my multimeter I do not see 12V at the electrical connector to the injectors.

As you might recall, the wiring is a "bit of a mess" but I'd still really like to "patch" it & at least get the car running before committing (time & $$) to a new harness. Separately, I also verified (by removing lots of electrical tape) that there is NO main 25A inline fuse, but simply two red wires spliced together (spliced is too kind a description really, let's just say they are twisted together) just underneath the black bus box on the fender.

So, I believe my next step is to get power to the injectors, and only then will I even be able to see if they are being correctly grounded - and allowing fuel into the equation.

My first question is what do you think is the best way to get power to them? Given the state of the wiring, I am reluctant to disturb it too much.

I downloaded a wiring diagram, but beyond my lack of proficiency, it also seems very simplistic. I see that the four green/white wires from injectors turn into one green/white and it heads to junction 13 at the Jetronic (ECU). Other side of injector connector Yel/Red wires go to idling valve, lambda (O2 sensor), fuse #4 (which is intact), and Main relay (which has been replaced and I believe is good). But I can't see/comprehend which actual connectors are used at the junction points. For instance, none of the injectors have power, so I want to tap / bridge the common points, not to each injector.

So, given that I know that replacing the whole harness is the best way to go, are there any suggestions for a fairly unobtrusive way (basically short of pulling the intake off in order to expose all the injector wiring & manually trace it) for additional points to test for 12V power and/or where I need to jumper to get power to the injectors correctly?

Second question, I assume the PO removed the 25A fuse because it was blowing regularly (maybe due to corroded wiring?!?), but wouldn't that just move whatever problem there was further down the line? And any thoughts on where that problem might be (other than my injectors!) It's occurred to me that the original problem with the pumps & relay (which weren't working) could be traced to the lack of that fuse, and I don't want to damage my new parts.

Again, I appreciate anyone's help who is willing to chime it, even if you are simply going to tell me I am mad to keep trying this half-assed incremental patchwork approach. I know this car is currently more than one set of problems (probably conflicting) at the same time which complicates things ridiculously, but I just feel if I could get her running I'd feel so much better about all the other little bits & pieces that need to be done, & then I'd pony up for a harness and do that work too.

Thanks all!

 

The four white green wires into one is the ground to the ECU. You need to look for a short or break in that wire. You could do point to point continuity tests to help. Note; don't use a needle type meter, use a digital. old-style meters can fry the ECU.

Test
WITH THE IGNITION OFF:

ECU 13 to main relay socket 87 = 4 Ohms(injectors)
ECU 10 to main relay socket 87/2 = approx. 20 Ohms(air valve)
ECU 23 to main relay socket 87/2 = approx 20 Ohms(air valve)

 

never assume. I've seen people do some HORRIBLE things to car wiring because they are afraid of electronics or think its all magic.

the power from that (missing) 25A fuse goes to the fuel pump relay, which is actually two relays internally. one half of it turns on with the ignition key and provides power for the ECU, the injectors, the idle air control valve, MAF, etc. the OTHER half is turned on when the engine is turning over and powers the fuel pumps.

 

Thought I'd update you that I did get the car running. Appreciated all the help, and you'll likely get a good chuckle at my stumblings. New question at the end too. ;-)

It was very rough at low idle, and from searching the board here I suspect it's simply a case of air getting around the meter in various ways. I was just pleased to hear it run, and it smoothed out with some revs.

In terms of how, it was a little bit of a kludge, & temporary for sure - cue chuckles.

The red wire bullet-style connection at grey firewall box (in my car 4 of 6 possible connectors are used) was /very/ poor. So I disconnected there and measured 12V back to fuse box (driver side) when key in "on" position, but once I re-connected (even after cleaning the connections) the voltage dropped to about 2V. So I suspected that the wire was grounding between that connection and the injectors, and I started stripping the black plastic to see if I could find where I would need to jumper a good wire. I started to remove the intake to get better access and then saw that wouldn't help - why did Volvo loop those wires around the intake?!? More peering & fiddling & I saw that the wiring actually looked pretty decent, no broken insulation that I could see - but I couldn't get underneath the #3 or #4 intake tube to see the possible connection point.

In my mind, I thought that one side (front) of each of the injectors would terminate at that red wire for 12V. But then I noticed two large (small gauge, right?) wires matching the injector wire colors (I'd carefully pulled back one injector's rubber wiring boot to see the colors) heading back over to the passenger side firewall and through to the ECU. The back one was the green/white Ground, the front one was the one that I thought would be getting power. Of course, as I write this I am sure it IS getting power from the red wire, but ALSO going into one wire heading back to that relay Pierce mentions above.

At the time, I'm somewhat puzzled at this point, but I at least stopped pulling insulation off - and I considered again how decent looking the wiring I am uncovering seems to be. So putting aside temporarily "how" & "where" this wire is supplying power to the injectors (I can't seem to get there anyway, and it all looks like nice wiring), I wondered if the "short" or "issue" was actually heading back to the fuse box (the much uglier wire as far as shielding) and it wasn't manifesting /until/ I put a load on it! So I hot wired from the battery to the nice looking passenger side of the red wire at the grey connector.

Turned the key, and she started on the second or third try - albeit roughly. Blind squirrels & nuts, eh? :-)

Next was to get the car up on ramps (towed it 10' up the driveway & rolled down onto them) to look underneath (where unfortunately I discovered a LOT of rust on the floor just behind driver seat) as I bought the car having been told the shifter bushings were bad, so that was the next thing to look at now that I know it runs.

And there is the next question - the linkage does indeed look a little worn, but with my young son in the driver's seat and me underneath I can see that the shifter is moving the input shaft just fine, and the clutch cable looks to be moving a normal amount. But, there are NO selectable gears. No matter where the gear shift is moved, the car is in Neutral.

I searched here for M47 issues, but all I can find relates to not being able to shift into a single gear, or a very wobbly shifter. I have no frame of reference for the wobbliness of the shifter, but I don't think it is horrendous, and I can SEE the input shaft moving with the shift lever. But I have no gears whatsoever.

Ideas on possible causes? Ways to troubleshoot? My worry, of course, is that the issue is internal to the tranny & I'll be pulling engine & tranny to have any chance of fixing it. As always, I appreciate the insight of the board - and Pierce, special thanks to you.

Oh, and on the red wire, I'll be tracking the path back to the fuse box now, will replace it in that direction and see what happens, clean all the grounds that I can find (I have done a few already, firewall, intake, etc.), and clean all the fuses properly too.

 

you might jack up a back wheel, spin it and see if the drive shaft is turning where it goes into the back of the transmission. I've been known to spin the wheel with a foot while on my back looking up under there. of course, put the car on a jack stand before crawling under it!!

otherwise, transmissions are way above my pay grade. with the engine off, if you try shifting without the clutch, does it feel 'blocked' going into gears?