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max29a's Avatar
 
Join Date: Jul 2004
Location: Santa Barbara, CA
Posts: 90
one more try, help diagnose engine power loss

Hello again,

I am have been and am having this problem where my car will spontaneously loose engine power while I am driving or just idling. I would like to describe my symptoms in detail one more time and see if anyone has ideas for me:

EVERY time the engine looses power, the loss happens right as/after I hear a relay click. Sometimes the relay will then click rapidly while the engine stays dead (electrical power still on, radio works etc) and sometimes it only clicks once on power loss and once again when the engine comes back.

sometimes there is a violent bucking, but more often the engine power will just smoothly go away and the rpms will begin to drop steadily. I will generally still be pressing the gas pedal down but it will have no effect. Sometimes feathering or just letting off and pushing back down of the gas pedal will coincide with the engine coming back to life, I am not sure if its actually causing it.

occaisionally the engine will not come back and I will have to wait for it to fully reach 0 rpms and the ! light comes on. If I am rolling still I will pop it out and back in gear and "push-start" it. If I am stopped I will turn the key off and back on. This almost always works.

very rarely I have to wait 2-5 minutes before turning it off and back on will work. When this happens it will crank all it wants but never fire up.

Someone suggested fuel pump might be starting to go?

What do you all think? I am very green as far as wrenching goes but I do have access to a full garage as well as hopefully getting together with Danno soon, so please give me anything you can think of to check.

Finally here is a list of stuff I have done so far:
new fuel filter (are there more filters inline that I might need to change?)
new coil and wires
previous owner: new cap and rotor
new battery
new TPS
2 new DME relays
check solder joints in DME itself
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1985.5 944 NA - 270k miles!
2001 suzuki sv650 - 37k miles

oil change done at 270k
timing belt done at 240k
Old 04-06-2005, 08:08 AM
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Uhmmmm relay clicking.

Ignition switch.

The primary stage on the relay powers the dme, the secondary stage on the relay powers the fuel pump. My guess is something is shorting out basicly turning the ignition swithc on/off. The car stalls out.

Check the wiring. But wiggle the key in the ignition while its running.
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Old 04-06-2005, 09:23 AM
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It's been common for the receivers for the relays to NOT clamp firmly on the relay's blade shaped pins. Especially in the under hood relay/fuse box.
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Old 04-06-2005, 12:56 PM
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I got in my car, fired her up and wiggled the key in the ignition. Is this what you wanted? it wiggles quite a bit but nothing happened.

I also opened the relay box and wiggled all the relays including the DME relay. Still nothing.

I did notice something new. My power brakes are broken! this piece is cracked and leaking vacuum? air?

Here is a picture:

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1985.5 944 NA - 270k miles!
2001 suzuki sv650 - 37k miles

oil change done at 270k
timing belt done at 240k

Last edited by max29a; 04-06-2005 at 04:22 PM..
Old 04-06-2005, 04:04 PM
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You dont have a aftermarket alarm in the car do you??
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Old 04-06-2005, 05:27 PM
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no aftermarket alarm, no alarm at all.

there is a new stereo with amp (alpine) that looks well installed. Its been in the car for at least 2 years...

I think that is the only real "upgrade" to the car. Everything else is stock.

the cruise control seems to come and go as it pleases. I wonder if that could be related at all or symptomatic?

I don't know how long that vacuum has been leaking. My brakes only started feeling bad this morning, but boy my idle sure is nice now that I plugged it!
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1985.5 944 NA - 270k miles!
2001 suzuki sv650 - 37k miles

oil change done at 270k
timing belt done at 240k
Old 04-06-2005, 05:30 PM
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Definately replace that valve. Though that is not causing your hesitation problems.

As AE1969 suggested, I would start wiggling your ignition when this happens and see if it corrects itself.

Failing that, I would suggest that you check the following,

Throttle position switch
Fuel pump

Yes, there is another fuel filter. it is in the fuel tank. Where the hose comes out of the tank and connects to the fuel pump. Notice a 17mm "nut" on it - it is removable. Obviously, you want to do that when the tank is as close to sucking fumes as possible.

AFJuvat
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Old 04-06-2005, 06:43 PM
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Can I get some help on part number to replace my valve please? I can't find it.

I have been trying to wiggle the ignition switch when the engine cuts out on me, but what am I looking to happen? It doesnt seem to do anything. I am thinking I will open it up this weekend and see if I can see anything cracked or any loose connections.
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1985.5 944 NA - 270k miles!
2001 suzuki sv650 - 37k miles

oil change done at 270k
timing belt done at 240k
Old 04-07-2005, 07:29 AM
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