91 740 base wagon, Non turbo, won't start

cgreygoose · Post by **cgreygoose** » 21 Mar 2012, 09:51

Hello, it's been awhile since my last post. I recently bought this 91 740 Non turbo wagon for cheap, it sat for a couple of years, but it wouldn't start. This is what I've done: drained the brown smelly gas, etc, cleaned the injectors, replaced fuel pressure regulator & plugs, new battery etc,. Fuel pump/filter underneath driverside back seat both work fine. I'm getting gas all the way up to the fuel rail but my injectors are not opening, I can also disconnect fuel line at the fuel pressure regulator and gas will surge out there too. After a few cranks the plugs are still dry. When I spray starting fluid into the throttle body the car starts up right away then dies. I'm going to have my friend bring his multi meter over tonight to confirm if my injectors are getting power.

Should they not be getting the signal to spray what's my first step? I've read about the air control valve,, crank position sensor etc, but I want to start with what's the most likely culprit.(s). then go down the list of things to check off.

Post by **billofdurham** » 21 Mar 2012, 12:47

Check the radio suppressor relay. It is actually an injector relay which was put into the circuit to stop the injectors interfering with the radio.

740 '91 radio suppressor relay.pdf: (229.45 KiB) Downloaded 151 times

It is usually mounted alongside the cooling fan relay which, up to 1991, was the same part number. The easy way to check is to switch the two relays, assuming the cooling fan relay is OK.

If there is doubt about the cooling fan relay you can jumper the two larger wires leading into the radio suppressor relay connector. If the engine then is able to start, your relay is defective. If not, your problem is elsewhere. Don't leave the jumper in place or your battery will discharge: this is for testing only. If you do use a jumper and the fan starts, you've jumpered the wrong connector.

Bill.

cgreygoose · Post by **cgreygoose** » 24 Mar 2012, 20:32

well I went ahead and switched the pigtails on the radio supressor relay with no luck. I did get a multi meter from my friend to check for a signal at the injectors but between the rain and life, I was unable to do much with it yet. I assume that I can find the steps necessary on how to check for power to the injectors etc, and what to do if or if NOT there is a signal but do you have a quick answer to that? I did purchase the crank position sensor but I don't want to install it and that not be the solution because it's non-returnable once it's been used. Is there a way to use the meter to confirm if that sensor is working properly? I've got to find a haynes book for my 89 &91 740 as my 240 manual is not concise enough. I'll mess around with it tomorrow and check back with any results.

cgreygoose · Post by **cgreygoose** » 25 Mar 2012, 10:02

OK. I purchased the new Crank Position Sensor an I';m glad I did. The old one was frayed really badly, showing the wires etc. So, I replaced it and went to start the car and nothing. I took out the meter & checked the ohms on the injectors an I got a reading of 15.7 on each one, which seems about right but I don't have a manual for this model.

I paid close attention to the dash when trying to start the engine and my idiot lights along the bottom start flashing in a pattern, the speedometer goes haywire as does the fuel gauge. I don't believe this ever happened before. What does this mean? Where do I go next?

I really need an appreciate the help on this forum. If I can't get this car running then I'm in the hole and will have to sell it at a loss. I don't have the time to part it out either.

thanks again.

jason

cgreygoose · Post by **cgreygoose** » 03 Apr 2012, 22:22

Well the latest news was that I ran out of funds to get her running, so it's been on hold a bit. I did check to see if I was getting voltage to the injectors, which I was. The resistance was also good. I disconnected the fuel rail from the engine while leaving the injectors plugged into the rail. Turned the key over and cranked it a few times and still no fuel out the injectors. So its got to be the injectors themselves still being plugged after all the cleaning that I've done. I need to find used ones now. That's the latest.

Does anyone know anything about my dash lights flashing? They all do it in unison. Speedometer goes berserk too. It's never done that before.

cgreygoose · Post by **cgreygoose** » 10 Apr 2012, 21:00

I finally got a hold of a set of used injectors and voila, the volvo started right up. IT's running very good now. I've got to do a long list of punch items to get the car to be my daily driver but it's running well as it is. So, glad I did not sell it for parts. Thanks again for each of you for taking the time to respond.

Post by **billofdurham** » 11 Apr 2012, 12:12

Good job. Thank you for the update.

Bill.

abbeyforbes · Post by **abbeyforbes** » 12 Apr 2012, 03:38

good for you! Congratulations!