After 375K miles and various relay replacements I would think this latest adventure would be a simple fix. Here's my story on my 1989 740 GL. Last week I stopped to fill up with gas. Started up and then stalled. Started again and went to leave and it stalled. Couple of mechanics came out and one banged on the fuel pump while I started the car. It started and I drove 5 miles to get it home and in the garage. Shut it down and wouldn't start again. So typical areas would be fuel pump relay , Radio suppression relay , fuel pump , fuel filter and CPS. I have extra of all of these parts so I started to do my usual replacement of the fuel pump relay. Fuel pump ran for a few seconds , relay clicked but no start. Replaced RSR and still no start. So I jumpered the fuel pump relay and pump ran ,still no start. Next jumpered out the RSR and still no start. So plugged in new relays and replaced bosch FP with new one. Also replaced CPS with one that I had. Checked and had spark , used a noid tester and had injector pulses. Went to start car and it started and ran for about 30-40 seconds and stopped . It sounded like I ran out of gas. Wouldn't start again In all it started about 3 times and as I mentioned it sounded like it ran out of gas. So here I am trying to rethink this to see what else could be the issue. OK frustration done and I'll get back to it after lunch. Sometimes you just got to walk away.

 

May be it just realized it had 375k, and got a panic attack? It happens to me when I remember how old I am...
You did the right thing by walking away, it will come to you. I can't think of much else besides what you've already done.
But, just because the pump runs doesn't mean that it's doing its job, may be a pressure issue, since you say it seems like running out of gas?

 

Yeah I'm thinking the same thing and trying to figure out how to rig up a fuel pressure gauge . Looks like the fuel rail has a special fitting where the flex hose hooks up the the steel rail. I'll play with it again tomorrow. Anyway I have a 2nd Bosch FP so maybe I'll check it out tomorrow. I have a full tank of gas so even if the tank pump goes it will still keep the line full. Once I check the pressure it should give me a guide to the next step.

 

OK still scratching my head here. Managed to rig up a pressure gauge on the FI fuel line and got a dead head pressure of 90 psi. That was done by jumping the FP relay socket to run the FP . So no issue with FP pressure as it should be the normal 43 psi with the FP regulator functioning. I went back and checked all of the usual areas of concern when you get a no start condition.
Noid check injectors and all OK so RS relay is functioning
Spark test plug and OK so CPS is functioning
Tried 4 different FP relays and all clicked when ign turned on. Even built hard wire plug with position 30 ,87/1 and 87/2 jumpered

So I checked fuse # 1 and # 11 with key off and key on. Here is where I'm scratchin my head. Fuse # 1 is always hot with key on or off. Looking at the schematic I think I'm reading that with ignition on fuse # 11 should be hot and it is not in either start or run mode. Also this feeds the 02 sensor which I haven't checked at it's connector. I need to sit down and study the wiring diagram and see what I'm missing. Hopefully I won't have to get into the ECU. OK a rest day tomorrow and I'll look at it next week. Sometimes it's nice to have 4 vehicles between the 2 of us.

 

MAFS? They can cause strange behavior sometimes.

 

Check your wiring to your Idle air control valve for breakage/ chaffed!!!!!! What your experiencing japoened to me exactly years ago!!!! I had to splice in new connector!!! Peace and blessings Osss

 

Well I had a few minutes to look back at the problem. I shot some starter fluid into the back of the throttle body and it fires right up and idles until it uses up the fluid. So at this point it is a fuel related issue. I have 6 FP relays and have check them all and they are all functioning correctly. I also have 4 RS relays and have checked them and they are working. So looking at the schematic something doesn't add up. The fuse for the FP relay is fuse #1. The fuse for the in tank FP is fuse #11. As I read the schematic it tells me in key position 2 (run) I should have +12V on fuse #1 and fuse #11. I only have power on fuse #1 but that should let the main FP run. So more hunting . I'll have to see what is not turning on fuse 11 . OK gotta dinner appointment.

 

Do you have a pink label ECU? I believe that '89 was the year with the pink label ECU that would develop problems with the fuel pump circuit. The symptoms you describe sound like this problem. If you have a spare, try swapping it.

 

Nope don't have an extra one of them , yet. I'll be into doing some circuit testing and see what comes up. Got all of the green books to do the testing so it's just a matter of time.

 

OK spent a 1/2 hour today and narrowed it down to an open circuit from the FP relay to fuse 11. So somewhere under the fuse block there is an open or broken wire. I'll need to remove/turn over the fuse box under the radio and sort out the issue. I hot wired my FP today and the car starts up and runs great. If it's something else I'll report back but for now that's the problem and I'll just fix it and wait for the next issue. Thanks for the discussion.

 

OK sorry for being a little late here but here is the follow up to this problem with the final results. After following the wiring under the fuse block I found it to all be in tact with no opens. So this pointed to the ECU where after doing various tests of the FP circuit the problem became a fault with the ECU in grounding out the FP circuit from the FP relay. Also after a internet search on volvo ECU's it appears that this is a common long rang fault dud to age. The ECU that I have in my 89 740GL was the white label 951 unit. The interim fix was to run a wire from the FP relay socket to ground. Doing this I found that the FP would run for 5 minutes after I shut off the engine so I installed a relay to open the ground circuit when I shut off the engine. Now this is a patch but I searched out a used rebuilt 951 ECU and am waiting for the delivery where I'll install it and put the circuit back to original. So the net is the problem is solved.

 

Good you got it solved! I hate ECU problems, luckily never had one, knock on wood!

 

re: 951, you should be able to use 933, 943, 946, 954 ECUs, probably others. pretty much any non-EGR, non-Turbo LH2.4. avoid pink label 561's, they are known problematic.

see https://www.volvoclub.org.uk/faq/Eng...ReferenceChart

 

OK got the rebuilt 951 today and removed the patch jumper and installed it. Started right up so case CLOSED. I'm considering sending mine back to get rebuilt/repaired as I see prices for these will keep going up. Happy motoring.

 

Would this work on an 86 245? I like the idea of running a ground shut off relay as well. genius!!

 

an 86 is LH 2.2, completely different ECU series.

the ground signal he's talking about is the control signal from the ECU that turns on the fuel pump relay. I've never heard of his symptoms before, of the pump running after the engine has stopped

 

First I have a 1989 740GL sedan with Bosch system. As I mention the ECU is the 951 unit. The problem I had was the fuel pump relay position 86/2 was not grounding with the key on in start or run. The wire from the relay to the ECU was good but the ECU would not ground it out. So I ran a jumper from the back of the fuse block on the FPR pos. 86/2 to chassis ground. The fuel pump ran as soon as the key was turned and the car started. When I turned off the engine the FP continued to run for about 5 minutes and then stopped. When I installed the rebuilt 951 ECU and removed the jumper the car started as the system was designed. The fuel pump ran for a few seconds to charge the fuel rail and the car started. At shut down the FP stopped.

 

I was replying to 1967_Tempest who was asking if he could do this on a 1986...

 

OK , thanks.

 

my car had been sitting and the PO couldnt get it started. I replaced the coil, which the spark got way hotter and still no start. I took a tack hammer and tapped on each injector and it fired right up. Shut it down so I could attach the water pump pulley and the belts and fill it with water.

I was all set to do my tune up and the starter died.

I took it apart thinking it was filled with moss and brush debris, but one of the brushes broke off and kind ruined the stater. New one will be here Wednesday.

Thanks!! as the stuff in this thread did allow me to rule out a bunch of stuff!!