Greetings:

I have a '91 740 Rex/Regina car (192K miles) that usually won't start on the first start of the day without a shot of starting fluid. After that, it will start and run fine for the rest of the day. The ambient temperature does not matter - it does this regardless of whether it is 30F or 90F outside.

I ran the diagnostic tests on the box under the hood and am not getting any fault codes in sockets 2 and 6 (just 1-1-1). I replaced the coolant temperature sensor on the head (the one that the computer uses, not the one that just controls the gauge in the dash) as well as the fuel pump relay. The RPM sensor was recently replaced as well. The fuel pump was also replaced earlier in the car's life - so it is not original. The Radio Supression Relay was replaced a few years back - and I also tried another good one to no avail.

Any thoughts on what this could be? I doubt it is a problem with the cold start valve as I don't think it normally comes on over 32F. I would rent a fuel pressure gauge to check the fuel pressure, but I do not see a test port on the fuel rail.

Thanks for any suggestions.

Andrew S.

Just a thought, since I have overcome every flakey fuel and ignition problem possible on a 1992 Regina 745. Could the vacuum line from the Manifold Pressure Sensor be leaking at the intake manifold? It's an oddball little rubber part, no longer available, but could fool the computer to an incorrect reading, thus requiring a richer mixture. After the engine warms, the mixture is OK. I put small hose clamps on all the vacuum fittings. The cold weather start valve is another issue altogether. Volvo disconnected mine and zapped the ecu to ignore it. I also had to replace the Rex/Regina ignition module after it displayed odd cold start issues and stalling. Rex/Regina was not one of Volvo's better ideas. Now at 230,000 miles my 745 runs great and hasn't cost me a dime for service ((except oil changes) for two years. Starts cold without a problem. Finding the right fixes was a long slog, but the result was worth it.

Quick update: The car started cold perfectly for two days in a row. I have no explanation for this as I didn't change anything in that time period. Since this is a fourth car these days and is not being used much, I am wondering if it needs to be driven more frequently. I have to go on a 110 mile round-trip drive ths afternoon, I think I will use it for that. I am also going to try to clean the idle air control valve as perhaps that is intermittently sticking shut - and once it warms up is OK for the rest of the day.

I hate intermittent problems...

Another update:

I drove the car on a 110 mile trip on Thursday and it started and ran fine. It has been starting perfectly now so I am not sure what happened. The only thing that further investigation turned up was a dirty Idle Air Control valve. I cleaned that thoroughly with Throttle Body Cleaner and q-tips and reinstalled it after soaking the hoses in Simple Green and flushing them out. Perhaps it was sticking shut intermittently? I am not totally convinced this was the problem either because opening the throttle while cranking during a no-start episode did not seem to have any affect.

I am glad that the car now seems to be running fine, but I would prefer to know why it wasn't starting before. Throwing parts at it didn't solve the problem - at least initially. Could an overall lack of use have been the culprit?

Thanks to all for the advice - I am calling it solved for now.

Andrew S.

"Could an overall lack of use have been the culprit?"

This is very unlikely. Unless you are talking many months.

One scenario is that you had a problem that actually fixed when throwing parts at it but the cranking with no start "washed" the cylinder walls of all the oil. Suddenly enough compression for starting on fuel injected gas does not exist but the more volatile starting fluid was just enough to get the car going that first "dry" start and normal operations restored the oil film on the cylinder walls.

This scenario is possible but relatively unlikely.

Nope - it hasn't ever sat for months without being started. Typically, I try to run it at least once a week but sometimes it has sat for a couple of weeks between uses. When I do run it, if I am unable to drive it for 10 - 15 minutes I am always sure to at least let it warm up thoroughly and run it at a fast idle for 5 - 10 minutes to help drive out moisture and fuel dilution. If possble, I do try to take it for a drive rather than just a fast idle in the driveway.

As far s fuel washing the oil off of the cylinder walls when it won't start - I don't think this is happening since it doesn't smell rich once it does start and the oil never smells of fuel dilution as was somewhat common back in the days of carburetors.

As a quick update - it did it again yesterday. The car had sat for two or three days and didn't want to start right away. I tried tapping on the RSR under the hood. That didn't seem to help but after a few additional tries it started and ran fine.

We shall see if this happens regularly again...


Andrew S.

Final update: It has been running fine - and I did clean the IAC valve, so my thought is that it may have been that intermittently sticking closed the whole time.

Thanks again for all of the advice.

Andrew S.

Have you checked to see if the OXy sensor is working??I made the mistake of using meineke psuedo mechanics to change my header & they forgot to put the sensor into the new header,,,3 mos later I was using ether to start it & happened to peer under the car & saw it hnging from the ground w the tip ground off & the plug still in header..

Hi Blindboy:

Yes - the o2 sesor is the correct type and is working. That is interesting as I didn't think the O2 sensor could cause a stating problem.

I've got a Regina car, a 93. I'm thinking fuel pressure as you have replaced the main fuel relay and state the CPS is relatively new. These fuel pumps don't last forever. Can you check pressure at the Schrader valve on the fuel rail? You need 35 psi when running (or if you jump the fuses), but just as important, when blipping the throttle the pressure should go up, to 45 psi, if I recall correctly.

I'm guessing, you may not have enough fuel (pressure) at start up.

This assumes a good fuel pressure regulator (pull vac line and see if there is any fuel leaking, though my experience is they don't fail much). Mike

Hi Mike:

I will have to look again but I didn't see a Schrader valve on the fuel rail (which seems strange to me). The fuel pressure regulator does not leak gas out of the vacuum connection so it may be OK. If the car isn't getting enough fuel to start it seems strange that it will run fine even at wide open throttle under load without breaking up. I will have to go back through the receipts to see when (what mileage) the previous owner had the fuel pump replaced.

I will post back with my findings - thanks for the advice.

Andrew S.

740's don't have a Schrader valve on the fuel rail like the 940's do, unless someone has retrofitted a 940 fuel rail. You may have to use another test point like the fuel line to the cold start valve.
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Current rides: 2005 Volvo S80 2.5T, 2003 Volvo V70 2.4NA, 1973 Volvo 1800ES (fixed the ignition - now back to the brakes again)

Hi Chris:

I checked again and confirmed that this car does not have a fuel rail pressure test port (unfortunately). I am thinking that it has sufficient and steady fuel pressure though since the car runs fine including wide open throttle performance once it has started. If nothing else turns up as the culprit, I will have to find out how to test the fuel pressure on one of these to be sure.