I've had a few posts on here before, and had some great help, but unfortunately every time I think I have the problem solved, it confoundedly arises again.


Car: 1990 740 GL non turbo, Regina
Problem: Intermittently wont start
Current Suspect: Radio Suppression Relay Wiring (not the relay itself)

Problem history:

-Intermittently won't start the first time every once in a while, but starts eventually... until one day when it didn't and left me stranded at a mental hospital late at night.
-Car cranks but won't start. Couldn't find spark at the time so tried new distributor cap and rotor, checked plugs, even tried new starter coil. None of that worked.
-BCAA comes, and it starts fine for them.
-Wont start the next time, but eventually get it to start and drive it to the mechanic's where it starts fine for him each time. Guessing what the problem is he puts in a new master relay.
-I doubt this is the problem but the car works for a few months.
-Problems again, and it's determined that there's no gas getting to the injectors (sprayed some gas into the manifold and it starts on that gas, then dies) Try switching the radio suppression relay and the relay next to it (a fan relay?) but does not help
-Fuel pump relay seems to work, as the pump can be heard to run.
-Mechanic is convinced that it's a bad pump and replaces it but I think he checked the fuel pressure incorrectly.
-Car still wont start with new fuel pump, but he shows me that it's working.
-I switch the radio suppression relay with the relay next to it and the car starts! Problem solved?? No.
-Next time car wont start we open up the relay and see that one of them has a broken connection. Eureka! We found the problem! Soldered it and the car started and worked...for a couple weeks.
-Able to start the car eventually with some jiggling of the relay connection and the wires to/from it. Some contact cleaner on the connection (could it have been as simple as that?) keeps the car running for a few months.
-Next time the car wont start, I get my friend to crank the starter as I jump the two thick wires from the RSR, and viola it starts! Problem solved (I think), it was a bad relay or two this whole time. Jumping the wires together before I drive and disconnecting them when I park gets me through to the next day when I head out to buy a new relay.
-With the wires jumpered, the car wont start in the store parking lot.
-I jiggle things, wait a bit, and the car starts to drive me home and write this post.

The only thing I can surmise is that there is a problem with the wiring to/from the RSR or there is a loose connection on the other end of the wires. Does anyone have any ideas where I can go from here? What's the path of the wires to/from the RSP? Think it's just a coincidence that jiggling.patience eventually starts the car?

Having what I think is similar same problem..

I have had it running. then no start. Did not hear Fuel pump running. Checked RSR wires and they were loose.

I had in the past already taken off the bottom of the connector. Very crumbled. and just pushed the pins on tight.

Started up and ran to store. No start again. Checked wiring again, loose!

In crimping the connectors, must have bent the wires back and forth enough to cause them to nearly be metal fatigued completely apart. Crimped on some new connectors (happened to be at a Home depot)

but still no start and cannot hear fuel pump! I want to check wires, but forget which is which.

Top right (rounded part of relay plug is up) is Red, top left is green/red, and both are larger gauge.

Bottom right is black, bottom left is yellow/blue.

Jumping both top wires Red and green/red, should give me fuel pump running, right?

I can see my fuel pump relay operating, and the No. 1 fuse is good by the way.

What is the reading I am supposed to get between wires? or to ground?

jc

--
1985 740gle na, 1990 740gle 16 valve

Hi John,

I do not know if the 1990 cars are the same as the earlier ones, but...

On my son's 1988 745T I found a connector upstream from the RSR. The connections in it had degraded over time and was causing an intermittant no start situation.

Not sure of the location for certain but I think it was located under tehe hood at the cross brace on the driver's side.

Randy

I have a 91 740. It did the same thing. It would not start sometimes. I would wait a few minutes, did the Ford jiggle test. It would start. I finally figured out it was the crank sensor the whole time. This was 3 years ago. It is still running strong. Hope this helps.

hello
just cut off the connector and splice on some new ends.
this is common especially with that connector.
good luck
mike

Yes, the connection to the relay was circumspect. The rubber has deteriorated and it was possible that there wouldn't be a 100% connection 100% of the time. When I got my car started by jumping the two larger wires on the relay, I thought I had things figured out and I headed out to buy a new relay and some spade end connectors... but when the car failed to start without the relay in play, (the wires jumped) it further confused and aggravated me.

You did a very nice job at describing the problem and listing what you have done so far. I don't have any answers for you but I just sent you an email with a couple of attached .pdf files that might help.

Let me know if you have a problem with them.

Randy

Maybe the relay connector is SNAFU?

The relay socket pins are nothing more than crimp-on spade lugs
with a little spring lock tab on the back. Constant abuse can open the
lug so that it never makes a solid contact, and the crimp can get loose a
and benefit from some solder.

I reworked all of the socket pins in my fuse block, and soldered the crimps.
I ground down an old ten speed bike spoke like a long thin straight slot screwdriver maybe 1/16" wide slide it down the back of the lug to release the lock and remove the wire and lug for repair/soldering.

I'd like to find a source for replacement lugs..maybe T&B or AMP...
but no one has 'em around the usual electronics supply joints here.

Bill
Boston area

Volvo carries the lugs which you can source from a dealer. The parts diagrams show all the lugs used.
--
See the 700/900 "FAQ" at the menu bar top screen left side.

Failed to start even with the connector and relay not in play and the wires jumped.

You're sure it's a fuel issue?

Have you looked at the FI relay pin 3 Green Red wire with your voltmeter?
There should be 12.6 V there. then on through the right wheelhouse connector
a green/red to Pin 6, then to the green wires at the injectors.

There also must be a ground path (Grey wire at injectors)
Through pin 7 of the right wheelhouse connector (gray wire)
and back to the ECU pin 18

You may have a punk relay,bad ECU, loose connectors, bad grounds.
The meter will find it quickly if it stays broken.

If you havn't done it already, clean up the ground points on the
intake manifold The ECU has a black wire ground from PIN 17 to the
intake manifold ground point.

Bill