Date: Fri, 15 May 1998 18:19:55 +0200
From: "ōyvind Moxnes" <23moxnopsamne.no>
Subject: Re: Need Help Figuring out 1987 900T Puzzling Behavior


The next time the engine does a cut like you describe, look at the rpm-gauge. If it drops to 0 rpm this half second, you got an ignition problem. If it doesn't, you still migth have an ignition problem, but not for sure (most likely not). Try to disconnect the fuel-pump-relay and connect the fuel pump to the battery (the fuel-pump will now go all the time). Start up as usual. If it is okey now, it might be the fuel-pump-relay or bad connection somewhere. Another thing you/the garage can do, is to connect a pressure-gauge to the inlet-fuel-hose. If the pressure drops when the engine cuts......Then you know for sure what kind of problem it is. ōyvind Moxnes, Norway Tim Ricketts ,Wales, UK . wrote: > dbled wrote: > > > > I just recently discovered this group and have been lurking here a week > > or so and thought Iíd ask for some advice, opinions, or at least for > > some sympathy about an intermittent problem Iíve been having with my > > 1987 900T thatís been driving me and my mechanics crazy. > > When the car is cold, it always starts and runs OK. > > When Iím having the problem, the engine will momentarily cut-out as the > > engine starts to warm up (it starts about the time the temperature gauge > > starts to move towards operating temperature). This engine cut out only > > happens when thereís a constant load on the engine. It happens at any > > engine rpm and in any gear as long as thereís a constant load on the > > engine. The engine never cuts out when thereís a load on it (i.e. > > during acceleration, going up hills, etc.). it makes no difference > > whether the cruise control is on or off, the behavior is the same. This > > engine cut out continues as the engine reaches operating temperature. > > During this time, the engine isnít constantly cutting out. It will run > > OK for a few minutes and then go into the cut out mode for a while and > > then run Ok for a while. On 3 or 4 occasions (over a couple of years > > time), after Iíve parked the car (with a warm engine), it wonít restart > > unless I let the car set until the engine cools to ambient and then it > > starts right up. It may or may not exhibit the cut out behavior after > > restarting > > The best description of engine cut out is a momentary (half-second or > > less) shut-off of the engine. Itís as though the ignition switch is > > quickly turned off and on. Thereís no backfiring and the engine doesnít > > stumble or act as if itís running out of fuel; the engine seems to be > > either fully on (and running OK) or off. It may cut out once or twice > > and then run Ok for a while or it may cut out 5 or 6 times (resulting in > > a lot of jerking) before it settles down. > > Whatís particularly aggravating is that this behavior is erratic. I > > might go months with the car running perfectly and then Iíll get a rash > > of this engine cut out behavior for a while (a few days to weeks) and > > then the car will run fine for until the next episode (anywhere from a > > few weeks to months). > > Iíve taken the car to several garages (including the Saab dealer) when I > > íve been having this problem and of course, they can never duplicate it > > and they canít fix what ainít broken. On several occasions theyíve kept > > the car for a few days trying to get it to misbehave. They swear theyí > > ve done all the normal inspections, maintenance routines and replacement > > of fuel filters etc. Iíve also gone through the "bad" gas, water in the > > fuel, dirty injectors and other scenarios and still have the problem > > It strikes me that the problem is electrical (because of the nature of > > the engine cut outs) and its relation to engine temperature could point > > to some component sometimes failing when it gets warm. The intermittent > > nature of the problem is puzzling as is the fact that only constant load > > engine operation is affected. > > Iím sure thereís a clue or two here but we arenít smart enough to figure > > out what they mean. Anybody out there have any thoughts? > > Otherwise I guess Iíll just keep truckin until something breaks.

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