My 93 940 (non-turbo 160K miles) will not start. It was starting and running fine. Then all of a sudden it just refused to start. The engine turns over with no problem. A quick check revealed that it is firing. The fuel pump relay was replaced about a year ago. I checked the fuel pump relay as well as the auxiliary relay with a 12V battery and volt meter. Both appear to be functional. The fuel pump will run with the relay removed and a jumper in place. I have not checked the fuel pump pressure yet. The onboard diagnostics unit does not inbdicate a problem.
Does anyone have any other suggestions or had a similar experience??
Thanks in advance for any help.
GP

Thanks to all who relied to this post.
As I worked through this problem I discovered that there were 2 different fuel systems available on the 93 - 940's: Bosch or Regina.
The Bosch system has a true AMM (Air Mass Meter). The replacement part for the Bosch AMM is as low as $233 USD's from the online suppliers that I checked.
My 940 has the Regina system. The Regina system has what is reffered to as an "IAT" sensor (incoming air temperature ???) at the location in the intake system where the AMM would be in the Bosch system. None of the online suppliers that I checked offered the IAT. The Volvo dealer cost for this part was $47 USD's.
After all is said and done on this "exercise" and considering all of the things I did in an attempt to start the engine, disconnecting the IAT apparently was the "trick." Immediately after disconnecting the IAT the engine fired right up. So for right now I'm saying that was "it"!!
Thanks again for all of those that responded to this post!
GP
93 940; 96 850; 98 S70; 94 S-10 Pick-up

I had a similar problem - tried everything including ignition amp (power stage module), radio suppression relay, etc, to no avail. Turns out it was the fuel pump relay. Apparently two things will keep voltage from the coil - the radio suppression relay and the fuel pump relay. Simple problem, but very difficult to diagnose.

Sorry for the ignorance, but what the heck is the AMM.
I experience a similar problem, thoug my perception is that it's temperature dependent.

Thanks in advance

Sigbjørn

This part of the LH fuel injection system evaluates the amount of incoming air and sends its findings to the ECU (Electronic Control Unit). The ECU then adjusts fuel flow to the injectors as required for the current engine demands, temperature, etc.
--
Bruce Young,
940-NA (current)
'80 GLE V8 (Now gone)
'83 Turbo 245
'73 142 (98K)
'71 144 (track modified)
New 144 from '67 to '78
Used '62 122 from '63 to '67

Thanks Bruce

I replaced this some time ago and it's still intact. I have studied the information under "brickboard" more and are leaning to the theory of radio interference relay or fuel pump relay. So heopefully i will sort oyt the problems.

I find the pages end this forum excellent.

Sigbjørn

Unplug the AMM. If it starts and runs in "limp home mode" it's time for a new AMM.

mila,
You were right on! I unplugged the AMM and it cranked right up. The check engine light also decided to come on at the same time. Its now time to head out to my favorite Volvo store to make my contribution to the GNP!
Thanks again!
GP

My '93 940 NA did something like that. One morning it just refused to start. I went through the diagnostic procedures for the ignition and fuel injection with no trouble codes given. Then I did the diagnostic test where the ECU turns on various units like the injectors, fan radio suppression relay, etc in sequence and they all worked. Then I started the test sequence where, at one point, you need to run the starter to see if the position sensor (name right?) on the bell housing is working. At that point the engine started and has been running fine for several weeks. My 940 has the Rex-Regina system, not the Bosch.

I wonder why it "cured" itself. I do know I had no spark at the time it refused to start. I have been going through the car and cleaning every connector I can find. Then I grease them with silicone dielectric grease and reassemble. This was a mid-year change in 1993. Volvo has recommended doing this to earlier cars. As a result, the hunting Idle has disappeared.

Have you checked the radio suppression relay? It is subject to the same problems as the fuel pump relay. If this fails, the injectors will not run. You can try swapping it with the electric fan relay which is identical. On my 940 the RSR is on the passenger side strut tower near and below the coolant overflow tank.

Try spraying some stating fluid in the intake. If it starts and stay runnig it is the radio suppression relay, if it just dies after using up the fluid then it could be in the fuel system. Good luck.