Hi All, my car suffers from the well known intermittent no hot start. I have gone through the vey helpful FAQ's on which I have based myself to diagnose my Vovlo. RPM sensor, Fuel Injector (FI) Relay and Radio Interference Suppression Relay (RISR) seemed the most popular culprits. The FI relay was immediately replaced by a Volvo mechanic, but the very next day it happened again. The car always starts in the morning but intermittently refuses to start when 'hot' sometimes after a 5 min drive while other times 20 min drives. The first 3 times it happened they were spaced out by 4 weeks roughly, but lately it has occurred 3 time in 4 days. The Volvo mech has kept the car a whole day but wasn't able to get it to fail once!! As a result, he wasn't able to help me. In a desperate attempt to fake an RPM failure I disconnected the cable from the firewall, but the car won't start with it disconnected. I was told that no spark should be observed with an RPM failure, is that true? I did observe sparks during failure!!! I also performed the same naive test on the FI Temperature Sensor (FITS) and RISR. In the first case, the car started with the FITS disconnected; I was also 'lucky' to be able to test it when the car failed hoping it would start when disconnected: NOPE! With the RISR disconnected, not only I couldn't start the engine but its removal while running the engine would just stop the engine! The Volvo mech. was nice enough to lend me a 'light bulb' to connect to the injectors to see if they are powered during failure. Well, the bulb does light up during failure. One anecdote: today I was trying my darness to get the car to fail to further test it, I went for a 20 min drive came back and waited for 10, 20 and 40 min but it would not fail; so I decided to test the FI light bulb with all the injectors. I started with the FI closest to the front of the car; all went well (the car would struggle but would start!) until I reached the one closest to the firewall: the car failed!!! Is this coincidence or did I do something stupid? I thus proceeded to really test the light bulb, and it weakly lit up while the engine was cranking for all FI's. I disconnected the FITS as I was hoping that upon disconnection, that if the FITS was damaged and sending the wrong resistance to the computer, it would default to a reference value and the car would start: but the car still didn't start. I was about to test the spark again when the car started after only 15-20 min!!! Did the disconnection of the FITS had something to do with this? As you can see, I am quite desperate to fix it, I have only 1 car and my wife and kids have been stranded a few times, and I can't afford to buy another car. Please let me know of anything else I could test!
Thank you in advance!!!
1990 740 GLE intermittent no hot start
I forgot to mention that I did measure the resistance across the FI, FITS and RPM sensor: 16, 980 and 194 ohms with engine hot. I am wating for the engine to cool down to take amother set of measurements and will post them later.
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Guest
i had a slightly older volvo with the same problem. it turned out to be the in tank fuel pump relay. if you find where that is (usually under the passenger side dash), tap it next time you have this problem and the car should start. good luck
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Kmaniac in California USA
Reading your story was like de ja vu. I had a similar problem with my 1986 740 GLE, which is documented in the "1986 740 GLE inconsistant starting" post. You can read my experiences there.
I need to point out that your car has two fuel pumps, which work in series. There is a small pump in the gas tank, known as the "in-tank" pump. The other is the main fuel pump, which is mounted together with the fuel filter, in a cradle, bolted to the underside of the car, under the drivers seat. Both pumps receive electric power through the same fuel pump relay, which is found behind the ashtray in the console. Though powered through the same relay, each pump circuit is protected by separate fuses. Also, although both pumps work in series, the operation of both are not required for the car to run. The car will operate normally using the main fuel pump only. However, it will not run with just the in-tank pump only.
If you haven't done so already, check the fuse for the in-tank fuel pump. It is fuse number 11 in my 1986 740. Three days after buying my Volvo last August, I found the in-tank pump fuse blown. No telling how long this had been this way. Out of general principle, I pulled out the in-tank pump. I found the fuel pick up filter sock deteriorated with at least two holes in the sock. I suspect the deteriorated sock allowed debris to enter the pump and jam it, resulting in the blown fuse. Since I had the in-tank pump out, I replaced it and the filter sock.
My suggestion for you is to find and carry with you a rock, which is big enough to fit in your hand. The next time your car refuses to start, reach under your driver door, locate the main fuel pump, and strike the pump a few times with the rock. Then try to restart the car. If it starts right away, then your main fuel pump is the problem and should be replaced.
Please note, too, the main fuel filter is placed down stream of the main fuel pump. If the in-tank filter sock has deteriorated, unfiltered fuel will enter both the in-tank and main fuel pumps before seeing another filter. If you find that the main fuel pump needs replacement, it makes good sense to pull the in-tank pump and inspect the condition of the filter sock. And if you go to the trouble of pulling this pump, you may as well replace it and the filter sock for good measure. A new main fuel pump can be quickly destroyed by unfiltered fuel, if the in-tank fuel filter sock has deteriorated and is not replaced at the time of main fuel pump replacement.
The in-tank pump and filter sock cost me $50. The main fuel pump cost me $125. I put both in myself. Each pump took me about 4 hours of time each to replace, since this was the first time for me for each part. If you do this yourself, disconnect the fuel lines from the tank before removing the main fuel pump, to prevent the fuel from siphoning out of the tank. Work in a well ventilated area, free of ignition sources.
I hope this information can be of help to you. Please keep us posted on what you find.
I need to point out that your car has two fuel pumps, which work in series. There is a small pump in the gas tank, known as the "in-tank" pump. The other is the main fuel pump, which is mounted together with the fuel filter, in a cradle, bolted to the underside of the car, under the drivers seat. Both pumps receive electric power through the same fuel pump relay, which is found behind the ashtray in the console. Though powered through the same relay, each pump circuit is protected by separate fuses. Also, although both pumps work in series, the operation of both are not required for the car to run. The car will operate normally using the main fuel pump only. However, it will not run with just the in-tank pump only.
If you haven't done so already, check the fuse for the in-tank fuel pump. It is fuse number 11 in my 1986 740. Three days after buying my Volvo last August, I found the in-tank pump fuse blown. No telling how long this had been this way. Out of general principle, I pulled out the in-tank pump. I found the fuel pick up filter sock deteriorated with at least two holes in the sock. I suspect the deteriorated sock allowed debris to enter the pump and jam it, resulting in the blown fuse. Since I had the in-tank pump out, I replaced it and the filter sock.
My suggestion for you is to find and carry with you a rock, which is big enough to fit in your hand. The next time your car refuses to start, reach under your driver door, locate the main fuel pump, and strike the pump a few times with the rock. Then try to restart the car. If it starts right away, then your main fuel pump is the problem and should be replaced.
Please note, too, the main fuel filter is placed down stream of the main fuel pump. If the in-tank filter sock has deteriorated, unfiltered fuel will enter both the in-tank and main fuel pumps before seeing another filter. If you find that the main fuel pump needs replacement, it makes good sense to pull the in-tank pump and inspect the condition of the filter sock. And if you go to the trouble of pulling this pump, you may as well replace it and the filter sock for good measure. A new main fuel pump can be quickly destroyed by unfiltered fuel, if the in-tank fuel filter sock has deteriorated and is not replaced at the time of main fuel pump replacement.
The in-tank pump and filter sock cost me $50. The main fuel pump cost me $125. I put both in myself. Each pump took me about 4 hours of time each to replace, since this was the first time for me for each part. If you do this yourself, disconnect the fuel lines from the tank before removing the main fuel pump, to prevent the fuel from siphoning out of the tank. Work in a well ventilated area, free of ignition sources.
I hope this information can be of help to you. Please keep us posted on what you find.
Hi, I'm having a very similar problem (see my recent post "90 740 intermittent start problems - fuel?). You can read my post and see what I have done & the results. Let me know if when the car won't start it does right away if you spray starting fluid in the intake hose... that's exactly what mine does. I wouldn't call my a "hot start" problem necessarily because sometimes it won't start cold either. Also, is yours the B234 16 valve? Like you, I'm at my wit's end... I took it to the local mechanic and he immediately diagnoised the in-tank pump & replaced it... ($385) when that didn't work he disconnected the battery cable & reset the computer, this resulted in the car working fine for 2-3 weeks, then the no start problem returned. Like yours the interval between no starts is getting less & less. And like you I need this car and cannot afford a replacement or big dealer mechanic charge. Maybe together we can solve this...
Thanks, Dirk
Thanks, Dirk
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saad147
I have a 91 940 TURBO, and i believe where all in the same boat when it comes to old volvos and there mysterious streak of electrical problems. I have been having this same problem for quite some time now, and have tested a bunch of different parts to see which is the culprit. last weekend, i had a similar problem in my 99 passat 1.8T, I ended up taking that car to a local VW specialist and he immediately diagnosed it as the ICM. i thought about that for a while, and started testing the Ignition coil on my volvo, well lo and behold, i tested my ignition coil and the resistance reading is way off. its a sunday so I havent really had a chance to confirm it. but you guys may also want to check out this site. You may just need to clean your primary and secondary terminals.
check out this site.
http://www.vlvworld.com/indexframe.html ... 00_2_9.htm
check out this site.
http://www.vlvworld.com/indexframe.html ... 00_2_9.htm
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