oleo Posted August 11, 2016 Share Posted August 11, 2016 I have a 1998 Impreza ,EJ22, auto with electrical issues in the fuel pump circuit. Under acceleration off idle, the fuel pump relay flutters causing a fuel pressure drop which in turn causes the engine to stumble. It ONLY occurs under moderate to heavy acceleration off idle. And it stumbles really bad. I can accelerate lightly letting the rpms come up slowly and rev to the limit with smoothly with no issues. You can hear the relay fluttering as it happens. I have done all the obvious stuff. Checked all my grounds and power. Checked for bad pins. Tried several other relays. The signal from the ecm is good. I get the two second on when the ignition switch is turned to the on position. I suspect that the signal that tells the ecm that the engine is running may be getting interrupted during this condition. I haven't verified this because I'm not sure what that is. Tach signal? Anyone ever deal with this or have any ideas what I may be missing? I'm getting a little aggrevated here. Quote Link to comment Share on other sites More sharing options...
1 Lucky Texan Posted August 11, 2016 Share Posted August 11, 2016 hmmmm....I'd be interested in reading what the 'gurus' say but, I can't help thinking this could be an IACV issue. the fuel pump relay flutters causing a fuel pressure drop which in turn causes the engine to stumble.have you attached a gauge and SEEN the FP drop? Quote Link to comment Share on other sites More sharing options...
oleo Posted August 11, 2016 Author Share Posted August 11, 2016 Yes. I also verified by hooking up a power probe to the harness at the tank and watched the current fluctuate. That's how I realized the clicking I was hearing was the relay. I can hold the relay in my hand and feel it actuating. After trying a different relay and checking my grounds and power, I probed the connector and discovered the signal loss under the above conditions. Something with the idle air circuit cross my mind as well due to the the problem only occurring accelerating off idle. I haven't identified any issues there however. I'm starting to think it may be an ecm issue. Don't really want to go there but I do have another identical car with no issues I can swap with to check. Quote Link to comment Share on other sites More sharing options...
1 Lucky Texan Posted August 11, 2016 Share Posted August 11, 2016 (edited) hmm..maybe if the TPS has a dead/intermittent area just above idle - the ECM couldn't determine how much fuel is being demanded - but I'd expect he issue could be duplicated while parked. use an analog ohm meter to check the resistance of the TPS - it should be smooth thru its range. Edited August 11, 2016 by 1 Lucky Texan Quote Link to comment Share on other sites More sharing options...
Fairtax4me Posted August 12, 2016 Share Posted August 12, 2016 Need to figure out what you're losing. Power or ground. The control side of the relay is grounded by the ECU. If the ECU is losing ground you may get this problem. The ECU grounds to the intake manifold on the engine. On that year it should be on top near the right side of the ignition coil. Quote Link to comment Share on other sites More sharing options...
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