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I was driving several weeks ago, I pulled over, shut the engine off for about 10 minutes, it would not start afterwards. Called AAA, I was able to check for spark and the timing belt was fine. When the tow truck driver came, he asked me if the engine was getting gas. I told him I had no way of checking, he lay next to the car, after giving the gas tank a couple of good smacks, it started right up. He mentioned the in-tank gas pump seemed to be going out. I replaced the in-tank pump, switched the radio supressor relay with the fan relay, checked the relays under the ashtray, everything seems fine, but the car won't start. I can't hear the inline pump come on. I already ordered the RPM sensor. There are a couple of odd details: if I remove and tap the OD relay, then the car seems like it wants to start; the car will run for a few seconds if I shoot starting fluid in the intake(I assume that if the RPM sensor was dead, it would not run no matter what); I disconnected the fuel line from the fuel rail and no gas comes out when I crank the engine, I don't know if the RPM sensor is telling the gas pump not to run if the sensor is dead. The car is a 91 945T with 220K, I've had it for about 25K, have no idea of previous work done. Before this, the car had been running great.
Please help, I have replaced engines, trannys, clutches, etc; but I can't diangnose worth a damn!
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posted by
someone claiming to be Gustafkalle
on
Fri Sep 16 15:44 CST 2005 [ RELATED]
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Really tricky to tell whats wrong, for example: do you have a helper who is spraying the starting fluid continuously, then the car should really run a while until it stops, if the problem is in the fuel system. But if you sprayed yourself, it might just fire a second or two and then die. We need you to really paint us a good picture.
It sounds as if you don´t have enough fuel pressure, and then it is either the main fuel pump, the FPR, a clogged main filter, the relay, or a clogged in-tank fuel filte. In that order and IMHO. If not those guys, then there are a lot of more exclusive things to deal with by searching this board.
But paint us a better picture, systematically.
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posted by
someone claiming to be yeller
on
Fri Sep 16 05:36 CST 2005 [ RELATED]
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You should hear main pump when ignition is turned on. If you do check for 12V at in tank pump plug (under left pullout floor board by fuel filler pipe) at the same time. The pumps only run for a few seconds. Before you buy a new in tank pump check the continuity/resistance of the wire between the pump and plug and between the pump and ground. I have found open connections in the plastic fitting between inside and outside of the piece that you remove to change tank pump in 2 different 745's. Good luck Chris
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had similar problem in march. had to replace FI control unit...sorry...
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i prefer non-german cars
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If it runs on starting fluid the ignition is OK, including the RPM sender and Suppression relay.
I'd suspect the Fuel relay is failing, or (less likely) the FI ECU is failing to control the Fuel relay ground.
Even less likely (but known to happen) is a failure of the EZK Ignition CU's "Spark OK" signal to reach the FI ECU. I believe this was found to be a chafed wire leading from EZK CU (left side of car) to LH ECU (right side of car).
Note that this "wisdom" is from BB scanning and looking at the '93 B230FT wiring diagrams. Luckily I have had no 900 problems, thus no direct experience.
But I'd start with a new Fuel relay — or pull it, get the white cover off, and reflow the soldered points on the PC board. See 700/900 FAC for details.
--
Bruce Young
'93 940-NA (current), 240s (one V8), 140s, 122s, since '63.
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Check the fuel pump relay for solder cracks.
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See the 700/900 FAQ under 'Select Link' button on the top right.
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Hi there,
Have you tried jumping the fuel pumps and cranking the engine? If you do that and still have the same problem i would more likely blame the ecu. If it runs and does not quit fuel pump realy i sbad..
Goog luck
Sammy
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Just last night the IPD flyer detailed a similar case. The relay was the problem and the fan relay was also bad so switching them didn't fix it.
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'96 965, 16' wheels, Michelin Pilot Sports, rear 18mm bar + Koni, 201 HP cams, 129K. Put 200K on '85 745 TD.
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Thanks everyone, I really appreciate all the input! I will try repairing the fuel injection relay this weekend, also will try jumping the pumps. I hope the RPM sensor will arrive very soon.
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If it's starting consistantly with starting fluid, you have a fuel problem.
The RPM sender signal goes to the Ignition and has no direct effect on Fuel System. Of course if it's original and more than 10 years old (what year is your car, BTW?), then it should be replaced.
--
Bruce Young
'93 940-NA (current), 240s (one V8), 140s, 122s, since '63.
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I thought about the RPM sensor having nothing to do with the fuel, but at the same time I didn't know if the ignition sys wouldn't let gas go through if there was no need for it, ie no spark(RPM sensor). Sorry, it's a 91 945T.
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The car doesn't actually run with the starter fluid, it comes to half-life for a fraction of a second. The thing that throws me off, is that it actually wants to start once if I remove the Overdrive relay, tap it, and put it back in.
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Problem SOLVED!!
After replacing the in-tank fuel pump, RPM sensor, switch the fan and the supression relays, it turned out to be the fuel pump relay. At first I just reflowed the solder joints on the relay, that didn't do the trick. Then, I added solder to the joints and that did it. By the way, I had switched the fan and suppression relays and found out that the fan relay was bad.
As I mentioned in the original post, I can't diagnose worth a damn. I would have not gotten this far without all your help.
THANKS.
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