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Category: Volvo
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1994 volvo 940: 4cyl and it wont start i checked..fuel rail..presure

Customer Question

i have a 1994 volvo 940 model with 4cyl and it wont start i checked the spark and plugs it was fine checked the fuel rail and it had fuel and presure checked the timeing marks and they lined up i can fell the back fire in the air box when i try and start it but it wount start
Submitted: 8 years ago.
Category: Volvo
Expert:  AMEDEE replied 8 years ago.



We will have to pinpoint what the engine is missing.





All three of these are tested when the engine is being cranked over. There are two way of checking for fuel. Fuel pressure and fuel trigger. Both are very important and must be present for the car to start. Fuel pressure is self explanatory. You just hook up the gage and see what the reading is. Fuel trigger is check with a noid light. The injector gets unplugged and the noid light gets plugged in to the injector clip. With the engine cranking over, this light must blink. This is the signal to the injectors from the computer. You can have all the fuel pressure in the world, but it wont matter if the injector is not pulsing gas into the cylinder like it should! Compression tester, spark tester, fuel pressure gage and noid light are all accessible at your local auto store. All three tests play a very important part in diagnosing a no start condition. Be extremely careful when doing these tests.


Customer: replied 8 years ago.
i tested the fuel presure and it was fine also tested the conection for the injectors good voltage there. good volts going to the distributer and the wires are all new from the cap the the plugs and from the coil aswell new plugs spark is going to the plugs have not tested the compression but the car was running at the time about 1 year ago it was sitting for a wile i did drain the tank and filled with new fuel aswell the thing is that it is not the origanal motor in it. the car is a 93 and the motor is from the 95 model but it is the same motor the only thing the guy said that sold it to me. was that it use to have egr on it and he took it off when he put it in the car it never seem to run fine but turn on for the 1/2 hour to my house but parked it out side had to levee for school and did nothing to the car for about one year
Expert:  AMEDEE replied 8 years ago.

SO you have fuel pressure and good strong spark going to the spark plugs... correct? Will it run on starting fluid?


Have we checked the timing marks?

Customer: replied 8 years ago.
have not tryed the starting fluid but did check the time marks they all line up the belt looked newer
Expert:  AMEDEE replied 8 years ago.

Lets try some starting fluid and go from there.


Let me know!

Customer: replied 8 years ago.
tryed some starting fluid did not start changed the temp sensor still wont start it trys to start but if just stops and looks like the engine turns back a littel and then back foward over and over when u try to start it
Expert:  AMEDEE replied 8 years ago.

SO did you say that we have strong spark on all cylinders?


THe next step would be to check compression on all cylinders. If the valve timing is on and you have low compression, the engine just may be flooded and the cylinders may just be washed down with gas.



Customer: replied 8 years ago.
ok it has good compression and i have good spark i did notice when i move the wire harnest around i can sell more gas at times and other times i smell no gas i think it has somthing to do with the temp sensor read somwhere that it sends info to the fuel ecm and te inj.ecm how would i test that i checked ohms on it ad it looked high but so did other sensors checked with one at the junck yard and it was open where is the fuel ecm and how do i check if its bad
Expert:  AMEDEE replied 8 years ago.
Before we get ahead of ourselves, let me ask you this.... does it run on starting fluid?
Customer: replied 8 years ago.
at one point it started for few sec. and shut off then i tryed agien and it would not do it agien i did happen to change out the starter and maybe i move a brittel wire or somthing the main harnest gose by there. the back fireing seems to calm down when i move the wire in a spot
Expert:  AMEDEE replied 8 years ago.
WHat wire are you moving?
Customer: replied 8 years ago.
main harnes for all the sensors and the injtors thats is by the starter thats when i notices the gas smell was greater
Expert:  AMEDEE replied 8 years ago.
Are there any codes in the computer?