Hello,
I am having a no start issue. I have read over most forums etc trying to find the cause. I have eliminated the pump. It spins when 12v is applied directly from the battery. I thought it was the pump relay because 87 was burnt and tried re-soldering ended up buying a new one but still not running. I have a spark. I have looked at the wiring diagrams but they do not seem to match the colors of my wires for the suppression relay. The wiring is original. I have two larger diameter wires and two smaller diameter wires. The small wires are as follows. Pin 2 is a blue and yellow wire. The other is a old red or brown. The larger wires are red and the other is gray. I believe the red is 30 as it has 12 V so it should be pin 4. If my logic is correct then the two wires I am not sure of have to be for pin 1 and 3? I see the caos is in the circuit for the pump as well. How to verify caos correct operation? What else may be preventing my pump from running? Ballast resister? Thanks in advance for any and all help

 

How's the wiring harness? Look at the wires behind the alternator and under the intake. If they are flaking off, the insulation that is, that may be your problem--'87 are bad for disintegrating insulation.

 

You should have two pumps on that car, even if one is gone, it'll at least sputter occasionaly with the other pump working.
Have you used a test lamp to verify you have no power at either pump? I would start there and work back.
See what codes teh car is sending.

Regards, Andrew.

 

Thanks for replying. I have figured out I have no voltage at 30 on the fuel pump relay. Finally got the suppression relay wiring worked out. Any suggestions were to look at wiring for 30? I will check the wiring around the altenator as well as anything else. I am not familiar enough to know where I can check for voltage at various points that would at least let me know what general area to look at the wiring to find the loss of power. It is blue and yellow going to 30 like the blue and yellow on the other relay but the relay has smaller diameter wire. Again any help is appreciated. Just spent the money to paint the whole car and need to use it for a long Christmas trip.

 

Thanks Ted. The relay base was numbered wrong and I have voltage to 30 but the relay will not stay engaged. Charged air over pressure maybe? where would it or its connector be located? Getting very frustrated. Just painted the car and need to take on a long trip for Christmas and my tie is running out. Timing belt is ok. Pulse sensor seems ok as the rpm gauge moves when trying to cranck. When I jump 30 the pump works. Has a new pump relay. After jumping the relay it will crank but not run. Thanks again everyone for the help.

 

Don't worry about your wiring harness as far as corrosion unless their has been some odd outside of the norm event to occur. The degrading wiring harness's were in 240's up until 88.

Bubba is probably way better with the lh stuff than i am as I've just started to get into it. But are you referring to pin 30 on the back of the relay board?
here's the complete 2.4 wiring diagram.


So what i ask now are the relays clicking when power is applied? Is your relay for the injectors working?

 

AS we see here you need either a white wire from pin 1 on your ecu or a brown wire from the distribution block. And coming out on pin 5 on the relay should be a pink wire feeding the....
Well you can see, I have no right looking at 740's

 

Thanks for the reply. I am new to this as well. The relay does click. I jump 30 to 87/2 and the pump spins and after I put the relay back in it will crank but immediately die because the relay clicks back off. I believe the suppression relay is ok but I am going to chort pins 3 and 4 to make sure.

 

I have a b230ft motor. Is this the correct diagram? I am using a different one that shows an air over pressure switch.

 

So far no codes? It has the old push button and lead type at the right a pillar.

 

Gauge is in the red. Pretty sure this is my problem but I cannot find it or the connector to try and jump to make sure. Called vovlo and they cant even find the part number in their system. Could it be called something else. Is it in the main large turbo hose with the mass air flow sensor? If it is not the switch then it would have to be the ecu right? Any one know where the CAOS is located on a 1990 740 turbo b230ft?

 

If the relay clicks off, it's probably the rpm sensor. Go to www.stepbystepvolvo.com for free guide to 740 no-starts.

 

 

The CAOS on my 1987 740 is under the driver's side dash, next to the Ignition Control Unit (above gas pedal). I have a photo of it (Figure 13) in my 740 no-start guide. I also have instructions for verifying the CAOS is at fault.

 

Thanks Fred. I have your instructions printed and I will try it tomorrow. It at least died in my yard but I do not have light or power so I will have to wait until tomorrow. I am frozen after being their most of the day. Mine does not look like yours. I looked around the pedal and ICM but I have 3 round items that may be the CAOS. Volvo sent me a fax but it was no help. Nothing looks like what they sent me either. I really need a picture of a unit like mine. Again I will verify the CAOS tomorrow and get back to you. Thanks again for replying.

 

I just though about it. I can't verify because I don't know where it is exactly. It should be in the same area as your step by step but I see nothing that looks like a two wire connector with a vacuum hose.

 

Thanks to everyone for their help. It was the suppression relay but by the time I figured that part out I had a new fuel pump relay and it was not correct. Put the old one I soldered back in. I still need to replace the terminal connectors for the suppresion relay. I went to two parts stores and they do not have the correct one. I had to use butt connectors but would like to find the correct terminal if anyone can point me in the right direction. Thanks again.