Hey everybody. Need some help from some smart guys. This thing was running great. Then it didn't. With engine idling (barely) figured that only two cylinders were operating and of the two that weren't neither fuel injector was working. Replaced said fuel injectors with no help. Now it won't start at all. Volvo step by step website offered no help. And the Chiltons manual is useless except for the diagnostics procedures.

When we did the diagnostics test for fuel injectors we got nothing. Function 3 wasn't indicating anything. The diagnostic system works because tests on other systems were successful. Is there something in the system that would prevent this diagnostic check from working? It seems as if the injectors are getting no power at all. And the manual gives me no indication of what values I should see on when checking the injector harnesses.

This is a B230FT motor. No add ons that we can tell.

Thanks...

 

Id be suspecting the 'fuel pump' relay (which is also the fuel injection control unit relay). if that relay is dead (or the fuse that powers it), the ECU doesn't get power, and the diags won't be alive.

 

Thanks pierce, I would have never thought about that one.

 

re: your barely running state... all 4 injectors are powered together, the same output of the ECU. on the turbos, there's a resistor bank which is over tucked up against the fender near the left headlight in series with the injectors. the injector power goes from the battery to the 'radio suppression relay' to that resistor bank then to the injectors, and the other side of the injectors are all wired together and pulsed to ground by the ECU to fire them. so I'm having trouble envisioning scenarios where some injectors would be working and others wouldn't.

 

I checked the resister yesterday. According to the manual read 5.5-6.5 ohms when checking plug from center blade to others. Checked out good. All spark plugs are firing as well. When we can get the engine to idle I can pull the connector from injectors 3 and 4 with no change. When I remove 1 or 2 the engine quits. Doing a compression test today when I get home.

On a side note, we were able to score a complete running motor and trans from an 89 740 Turbo Intercooler sedan for $250.00. We will be pulling all harnesses, relays and ECU as well. I imagine there would be more to a swap than just the engine and trans if we have to go that route.

 

Okay, finally got around to compression check. Results as follows:

#1 - 90 PSI
#2 - 120 PSI
#3 - 89 PSI
#4 - 90 PSI

I also pulled the timing cover and the marks are all aligning like they should.

#'s 3&4 are the cylinders not responding. Could it be possible that the head gasket has lost integrity between 3&4? If it's a head gasket it seems as a fairly straight forward repair. If not, I have another running motor from an 88. Is it possible to replace it with this one if I also swap all sensors, ignition, and fuel injectors? Visually the injectors are different. Looks like the block itself should bolt up to existing mounts, etc.

Thanks...

Tony V

 

an 88 turbo is LH2.2, while a 91 should be LH2.4, significant differences throughout the fuel injection system. the big difference in the engine block is that the LH2.4 uses a crank position sensor (CPS) thats between the engine and transmission, while LH2.2 used a hall sensor in the distributor. I don't know if you can retrofit the CPS onto a older block.

 

Thanks pierce. We'll have to check that out.

 

Figured it out. Had 3 & 4 plug wires crossed. I will now accept my dumbass award. Thanks for the help. We got new injectors and a spare motor out of all this. So it's not a total loss.

 

OH. hah, I wouldn't have thought of that one

 

Fairly common... I have bought a few Volvos with that problem, (very cheaply).