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I own a 1991 Volvo 740 sedan near Vancouver Canada. Occasionally, over the past year the car will just not start. It only happens once every 4 to 6 months or so. There is lots of battery power and fuel in the tank. It just seems like the engine is not getting any fuel to burn. There is no lead up symptoms to it occurring. The last time it happened I had it towed to the local mechanics and they went out to get the car in their yard and it started up right away. They checked everything they could (they are not Volvo mechanics - we live in a small town) and at different times (when hot, when cold, etc.) but could not make it NOT start, even though it would not start the day before. Now I'm having the same problem. I'll check the fuses #1 & #11 I believe from reading the manual, and I have been reading on the internet about the fuel injector relay possibly being a problem, but I haven't been able to find a photo of what it looks like and where it is located. Any ideas? Thanks, Murray

Submitted: 169 days and 5 hours ago.
Category: Volvo
Value: $15
Status: AWAITING CUSTOMER ACTION
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Optional Information

1991 4 door sedan

Already Tried:
Pumping the gas pedal. Jumping the battery. Taking it to a local mechanic (we live in a small town and there are no European vehicle specialists) and they could not figure out what it was. It does not happen very often, maybe once every 4 months or so.

Posted by AutoTech08 169 days ago.

Answer

 

Hi there,

 

The fuel injection system relay is located in dash fuse box, item E.

 

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When problem occurs, you need to check if it sparks that is missing or fuel related. Unplug a spark plu wire and attach a spark plug, ground it to the engine and crank. If sparks are not available, it could be the crank angle sensor that is intermittently failing.

 

You can try accessing the diagnostic to find if any codes are stored in system.

 

FUEL INJECTION, IGNITION & TURBO SYSTEMS

Fuel injection, ignition and turbo systems each feature a self-diagnostic function for fault tracing. A common diagnostic unit, located in engine compartment behind left strut assembly, is used to retrieve codes from each control unit. Diagnostic unit is equipped with an LED indicator, activation button and function select cable.

 

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Diagnostic unit output socket No. 2 is used for fuel injection. Socket No. 6 is used for ignition system. Socket No. 5 is used for turbo system. Once selector cable has been inserted in correct slot, depressing button once, twice or 3 times selects from one of 3 control (fault tracing) functions. Faults stored in either ECU memory are read by means of a system of LED flashes.

 

Diagnostic system for fuel injection ECU stores 17 different fault codes. Ignition ECU stores 9 fault codes. Turbo ECU stores 8 different fault codes. All fault codes have 3 digits. Each can range from 1-to-4. Example of 3-digit code: 4-1-3. Since all codes have 3 digits, each code requires 3 series of flashes. For easier reading, a 3-second interval separates each digit of the code.

 

 



Edited by AutoTech08 on 6/6/2009 at 8:25 AM

168 days and 14 hours ago.

Reply

Hi there. Thank you very much for your assistance. Unfortunately, I'm working alone on my car so I could not pull a spark plug wire and crank the engine at the same time (wel I guess I could lay it near the block and try to see through the window what is happening. Anyway, the good news is that both fuses # 1 and # 11 are ok. So, I found the self-diagnostic unit and plugged it in the sockets that you mentioned, number 2 and number 6 (I do not have turbo). The codes I received are confusing to me so perhaps I'll tell you what happened in detail and you could tell me what it means?

First, socket # 2, I depressed the button once and I received the codes 1-1-1. Then I reset everything and depressed the button twice and received continous flashing (it did not stop). Then I reset everything and depressed the button 3 times and received a strange code of about 25 very quick flashes for the first digit of the code (I could not tell exactly how many times it flashed, even after repeated attempts so I'll put a question mark after that number, then it flashed 4 times, and then it flashed very quick repeatedly again, then it flashed 8 times, and then repeated the same sequence. So, in conclusion, it up it flashed the code of 25?-4-25?-8, a four digit sequence of numbers.

Now, for socket # 6 I depressed the button once and I received the codes 1-1-1. Then I reset everything and depressed the button twice and received continous flashing (it did not stop). Then I reset everything and depressed the button 3 times and did not receive any flashing lights at all.

So, are you able to assist me with determining what these codes mean?

Thank you very much, Murray

Accepted Answer

 

Sorry if my earlier instructions were not clear. Whe code 1-1-1 shows, it means there are no codes stored. You should not have reset but continue with 2. Drive the vehicle around and redo the test again. If no codes are present, the problem should not be related with the PCM sensor circuit. It could be relays or wirings, fuel pump etc. Further test would have to be carried out.

 

Here is a description of the details.

 

Retrieving Codes

 

1. Locate the diagnostic unit and remove its cover. Connect selector cable to socket No. 2. Turn ignition to ON position. Enter control function No. 1 (retrieve codes) by pressing push button one time for at least one second and no more than 3 seconds.

 

2. Watch red LED and count number of flashes in 3-flash series. Flash series are separated by 3- second intervals. See Fig. 2 . Note all codes. Only 3 separate codes can be stored at once. If no codes are stored, LED will flash 1-1-1, indicating fuel system is operating properly.

 

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3. If a fault code is received, note them for reference. Depress push button again and check for additional codes. Depress push button a third time if necessary. If first code repeats, no other codes are present.

 

4. Diagnostic system memory is full when 3 codes are present. Those 3 codes must be repaired before further codes can be retrieved.

 

 

 

 

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Expert: AutoTech08
Pos. Feedback: 100.0 %
Accepts: 
Answered: 6/7/2009

Workshop owner

Diploma in Automotive Engineering, 30 years working experience.

167 days and 15 hours ago.

Reply

Thank you again.

What I mean by resetting is that in order to receive any codes I had to turn the key to starting the car to the "on" position (since it will not start, I turned it on as far as it would go - the headlights turn on, the dashboard warning lights turn on, etc.), then after I received the first code (1-1-1) by pushing the button once, I turned the key to the off position just to make sure that I "reset" the test. Then I turned the key "on" again and went out and pushed the button twice and noted the code (continous flashing), then went and turned the key "off" to reset the test. And so on.

I cannot drive the vehicle around and re-do the tests, since the vehicle will not start.

I now understand the idea of the codes. If I put the cable in "any" socket and press the button once and receive code "1-1-1" then that selection is operating ok. If I receive any other code than "1-1-1" there is a fault and reading the code will tell me what it is. I did not hold the button down for more than 5 seconds (I'm pretty sure) so it should not have "re-set" the diagnostic unit (I read this 5 second re-set procedure elsewhere on the internet).

So, it seems that socket 2 and 6 are showing me that those two areas are perforning properly since the first time I pressed the button when inserted in each socket it flashed the code "1-1-1".

I assume from your instructions that I do not have to go turn the key off and then on again in order to move to the next socket to test it. Is this correct? I can just leave the key on and test one socket, get the code, and pull out the cable and insert it in the next socket, puch the button and get the code, pull the cable and insert in the next socket, etc., etc. without going and turning on and off the key? This will completely clarify the instructions to me.

Question; should I try all of the sockets to see if they are all giving me a "1-1-1" code? Then I have eliminated all of the items that could be faulty that this diagnostic unit tests for.

If all of the sockets give me a "1-1-1" code, what else can I do? Should I remove an end of a fuel line and see if trying to start the vehicle pumps gas out of the line - then I would know my fuel pump is working. If so, do you know the best location on the fuel line I should disconnect and describe the area to me? Or should I first go and get a neighbour to come over to help, disconnect the spark plug wire at the spark plug (I don't believe I have the tools for removing the spark plug), pull the rubber back from the end of the wire and hold the exposed end close to the engine block to see if there is a spark coming from the distributor?

Many thanks, I hope I can figure out why the vehicle will not start, because if it has electrical power going to the spark plugs and it is receiving fuel, I can't understand what else could be wrong.

Murray

167 days and 13 hours ago.

Reply

I pulled and re-inserted al of the fuses and the relay switch boxes/ towers that were with the fuses and the vehicle is now starting over and over. So I still don't know what it was that went wrong other than it could have been a loose switch/ box. If it happens again, that is the first thing I will do, make sure that everything in the fuse box area has not been knocked off kilter.

Many thanks anyway,
Murray

Posted by AutoTech08 166 days and 19 hours ago.

Info Request

 

Sorry for getting back to you late.

 

No, you need not turn key off. Just keep a record of the diagnostic procedure and follow accordingly and you should be able to get into diagnostics.

 

Yes, you can try all sockets to check if any codes from fuel or ignition are present.

 

If none are found and you are still not able to start, it would not be from the control system circuits. It could be a loose connection with the relays.

 

Checking the fuel pressure would be best done at the return hose. Unplug the return hose and if fuel comes out when cranking, the fuel pump should be working.

 

To test the sparks, it would be easier if you have someone helping you and to attach a spark plug would be the easiest. A spare spark plug would do. A screw driver inserted into the plug wire socket can be used as substitute, hold it about 1/4 inch away froma ground on the engine. When testing, always ground to engine and NEVER use the battery terminals to short it, it can blow up the battery. sparks should be bright blue and if it is orange or dull yellow, the ignition coil is weak and that can cause difficult or non starting.

 

From what you have done, I believe it is a loose connection somewhere and could be a failing relay which is working after some jolting from unplugging and plugging back in. If it is a relay, problem should be back in no time. If it is loose connections, it should take a longer time to return or might not even come back again.

 

 

 

 

 

 

 

 

 

 

 

 

166 days and 18 hours ago.

Reply

Yes, I believe it was just a loose relay switch in the fuse box area. Because after I pulled and re-inserted every fuse and made sure that every switch was seated properly in the fuse box area, it seemed to work.

I noticed when I pulled one of the spark plug wires off that it is an old wire with some cracking starting in the rubber and the metal connector actually pulled out of the wire and stayed attached to the spark plug. So I have a new set of wires on order and will install them on Tuesday.

If it happens again, I will now check that all fuses are ok and seated properly, and check the diagnostic unit to see if all the codes are 1-1-1 before I do anything else. I managed to find on the internet which each code means from socket 2 and 6 and so I printed it off and will carry that in my glovebox.

So, I think I am prepared for next time.

Many thanks for your assistance.
Murray

Posted by AutoTech08 166 days and 18 hours ago.

Info Request

 

You are welcomed and thank you for the bonus.

 

It has been a pleasure working with you.

 

Thank you for using JustAnswer.

 

Have a nice day.

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