Resolved 1990 GSX 130k miles

[Nile]

Hey, wanted to get your thoughts on this. 1990 GSX. I apologize if this is the wrong section, excuse me moderators.

Went to get the oil changed today, car was running fine beforehand. Get to the shop, they don't have my oil filter stocked, so the guy leaves to buy one. I leave, fifteen minutes later the check engine light comes on, which has never happened. No real issues, just the light.

Get home around 4, car is sitting until 1030 when I go to work. Doesn't start. Strong starter, new battery, def sounds like no fuel. Sit and crank, nothing. Second time, small fire up, no start. Each time after produces a stronger fire up, until a very weak start. Runs for a few seconds, dies. On next try (4th/5th or so), she runs. Gives it gas, but bogs. Almost like hitting the pedal gave NEGATIVE power. Runs for a few more minutes, then gave some gas, and she revs fine. I didn't drive the car into work, just to be safe. Thoughts?

Also: what position is the oil gauge supposed to sit under normal conditions? When started, it sat right behind the "L"mark going towards the "H". One rev built noticeable movement forward. Another rev did the same. Didn't go all the way to the "H" though.

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[nitrouskris]

what are your mods ???

 

[Eeeeky]

Sounds like the coolant temp sensor. Not sure on the 1gs, but on a 2g, there are two. One for the gauge on the cluster, and for the ecu to control open/closed loop fuel. Try locating this sensor, and verify that its connected. If its just come disconnected, simply plug it back in, and your problem should be gone instantly. If its plugged in, try replacing it. I fought the identical problem with my 99GSX, $13 sensor later, problem gone.

 

[DSM1G90]

The CEL light worries me, which the ECU is going why you had those hard starts, loss of power until it settled down. What's the status on the ECU - original, or rebuilt/remanfactured?

Coolant sensors wouldn't cause bog downs, just hard starts when it's cold since if the sensor is bad the ECU thinks the water temp is at 77 degrees and doesn't need to go into rich mode (trick is with this is to barely hold down the gas pedal when hitting the key then it fires right up, but hold the pedal where the RPM's are about 1200 for a minute then let go .. it should settle to an idle by then...) causing the hard starts.

Next time for an oil change, buy the filter at NAPA - a 1381 filter and have them install that for you.. good for turbo setups.

Needle on gauge will be close to "L" during idle and about mid point or more when full pressure. It will never hit the "H". But, the gauge just shows pressure is present, not actual pressure readings. You could have the min of 10lbs at idle and the needle will not move, but as long as you take the oil cap off and see oil swirling around in the head at idle, you're good.

 

[Nile]

No real mods. Cool pack. EPROM ECU. Bought a fuel pump pretty cheap on a part out, going to see is this remedies the problem. A friend suffered from this before with an Eagle, so hopefully this is the same. If not, I'm going to check out the coolant temp sensors.

If this helps, car always had an odd idle. Like it wanted to die at times. The CEL came on initially WHILE driving, after the oil change. Went off after the car was turned off, then back on. After driving, came back on. But again, this makes me think it's a fuel issue. Let's bank on the pump for now.

Thank you all for your input. I'll keep you posted.
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[DSM1G90]

Back and forth CEL lighting could be knock sensor, o2 sensor...et.al?

have you, or know how to pull codes to see what the ECU is trying to tell you?

-DSM

 

[Hult250R]

Link on how to check CEL:
ECU Code Checking

This will at least give you a place to start.

 

[Nile]

Haven't tried pulling the codes myself, but I'm about to drop her off to get diagnosed now. Ill check back in with the results so others can have a place to reference if they see this issue. I know the suspense is killing you all!

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[DSM1G90]

I been using an analog VOM meter to see swings of the VOM needle, but now use the buzzer trick ....

 

[pauleyman]

Anytime you've got a CEL start there. A cheap analog voltmeter is all you need on a 1g.

 

[Nile]

Couldn't replicate the issue at the shop because it warmed up outside. Turns out :drumroll: engine coolant temp sensor. Go figure. Bought a fuel pump for nothing. But at least baby girl is running.

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