1986 Gl1200 SEI dying at not so high temps

[FlardaMan]

I have a 1986 SEI that I've been trying to get back to life. She runs better than she did when I got her however there is one issue I've yet to solve and that's when she gets to 4 bars on the temp gauge she is at risk of shutting off and not wanting to start until cool.
As of right now I've already replaced the fuel pump, checked the coolant pump (was fine), checked my GL GR sensors, NS and PB sensors, and even the TPS sensor. The tps sensor was hard out of tune, I assume from a previous owner, but so far none of that has turned anything up. The only other big thing I can think of is the coil packs overheating but that is an ordeal I have yet to get into. The only indication she is about to tap out is her idle cranks from 1000-1200rpm up to 1500-1600rpm.
I'm about to run into a wall with what to do, so I want input on what could be the issue before I go decide I'm stuck doing the coil packs.

[Rambozo]

When it shuts off, check for spark.

[joecoolsuncle]

i would first check accuracy of your temp gauge. establish a base

[FlardaMan]

As of right now I don't have an easy way verify accuracy of my temp gauge. And obnoxiously enough I couldn't make her overheat to test spark on supposed overheat. As of now I'm concerned maybe the Throttle Position Senor is just aged out and may need a replacement as coil packs shouldn't produce a higher idle under heat. However, an old and hot TPS could send incorrect data to the ecu thus resulting in the higher idle and possibly resulting in the fuel air mixture being funky to combust. This, however, is a guess based one the bike burning more and more rich as it got hotter.

[Rambozo]

If it gets richer as it gets hotter I would check the coolant temp sensor. I think there is a chart in the FI supplement where you could get the curve, then drop the sensor in a pot of water and measure it as you raise the temp.

[joecoolsuncle]

If it gets richer as it gets hotter I would check the coolant temp sensor. I think there is a chart in the FI supplement where you could get the curve, then drop the sensor in a pot of water and measure it as you raise the temp.

yes! an old hot rodders wives tale is to unplug the ect to trick the ecm into going closed loop. that will make the mix run richer and default to the limp home tuning in the ecm tables. it didnt work, but it would make more noise which the camaro guys interpreted as power. lol

always check for full voltage at the battery and check ect, before any further diagnostics on efi. get a baseline first or chase ur tail round and round throwing money at a problem you cannot find.
mr rambozo has written many posts that prove beyond doubt that he "gets it".

[Rednaxs60]

Thinking about your issue, but have not come to any sort of recommendation. These are the temp readings I took with my '85 Limited Edition FI model, not too scientific but gives me an indication of what is happening.

The temperatures I took with a therm imaging temp pistol are:

1 Bar: 41.6 deg C (106.9 deg F)
2 Bar: 46.8 deg C (116.2 deg F)
3 Bar: 55.3 deg C (131.4 deg F)
4 Bar: 68.1 deg C (154.6 deg F)
5 Bar: 90.5 deg C (194.9 deg F)
6 Bar: 98.1 deg C (208.6 deg F)

Fan on at 103.3 deg C (217.9 deg F)
Fan off at 92.7 deg C (198.6 deg F)

Good luck

[FlardaMan]

Alright then I'll go digging through my supplement manual . And so I understand proper you want me to put my sensor in a pot of water on a heat source so I can measure my voltage at specific temps?
I'll have to get my hands on a one of those temp guns so I can have a temperature comparison.

[Rednaxs60]

I have chased a few irritating issues with the CFI system. Have been through all components of the CFI system with a fine tooth comb. Have come to a realization that if the ECU does not generate an error code for any component it monitors, the CFI system is good.

Having mentioned this, the TPS can be an issue and not have an error code generated. A TPS failure will generally show up as the engine timing being out of sync. For a TPS that is failing because of the specific spot we all ride in, a new TPS is needed. If the TPS is faulty it can/will show up as the engine timing being off, and thenECU will fire a cylinder at the wrong time resulting in the engine almost stopping, have had this happen even with a new TPS installed - heat also affects the TPS. Aftermarket TPS can be good or faulty from the get go. Best to have a couple on hand when testing/replacing.

The TPS can affect the fuelling of the engine, but not a much as one would think. The calibration voltage of approximately 0.47 to 0.49 VDC does not allow for much wiggle room. You can be outside this a bit, but too much and an error code will be generated.

Another issue wth these FI models is the understanding of which set screw to adjust for idle or cylinder bank balance. Many have used the cylinder bank balance screw behind the right side CFI cover to adjust the idle instead of the idle screw in the middle rear of the air chamber. Recommend a set of vacuum gauges be used to check the cylinder bank adjustment. You cannot balance the cylinders on the same side.

You mention the TPS out of calibration, and that you checked it. It is mentioned in the Supplement that to calibrate the TPS you need to bring the throttle plate lever down to the TPS set screw. You must not adjust the set screw to calibrate the TPS. If the set screw has been adjusted in error, you need to set it back to the position it was set at the factory, PITA - BTDT. The set screw end that the throttle plate lever will be brought down to is about 7 mm proud:

The air inlet temp and coolant temp sensors are tested the same way. May want to check both as mentioned. Don't think this is part of the issue.

Check all your vacuum hoses, an increase in RPM is generally from this. 37 year hoses are not that reliable and new vacuum hoses can't hurt - recommend 3 mm ID.

An increase in engine RPM can also result from the fuel pressure regulating valve loosing the engine vacuum from a leak in the vacuum hose to the FPR. There is an increase in fuel rail pressure and the engine RPM will increase.

Good luck.

[FlardaMan]

I'm thinking half of my issue is from previous owner then, as my throttle stop screw has definately been moved way too far. Guess that explains why the tps sensor was so far off. I'd believe the vacuum lines being funky, she has all of 126k miles on her and the more I've worked on her the more I notice she has some stock things that shouldn't be stock.
You gave a ton of good info and I greatly appreciate that. I'm going to still test temps according to my temp gauge and see what comes up.

[Rednaxs60]

Thanks. The TPS a still function correctly and be calibrated with the throttle plate stop screw out of adjustment, don't ask how I know. Reset the throttle plate stop screw as per the picture and it will be close.

Doesn't hurt to check all sensors to get a good baseline. Little tricky getting at the coolant temp sensor in behind all the injector parts/pieces.

Keep us informed.

[FlardaMan]

I've started going after the vacuum lines today and I'm not fully certain they are the culprit. That being said I'm still going to replace them and give her a test to see if there is a change. I'm going to see about testing fuel pressure and fixing my throttle stop screw at the same time.
Last time I took her for a ride I did notice an odd detail. The second my temp gauge went up a tick the idle went up 200 rpm. My thermostat is reading correctly as it's right on par with Rednaxs60's temp readings so I'm not super sure what that's all about but I'll find out eventually.

[Rednaxs60]

Think about doing a left/right cylinder bank balance - cannot balance the cylinders on each side. This throws the cylinder firing out of whack. You can change the cylinder bank loading when the cylinder bank balance is not in spec. Two vacuum gauges one for each side. The cylinder banks are in balance when the vacuum is within 1 1/2 in go HG. Can get closer than this. May have to adjust the idle adjusting screw after the fact as well that is located at the rear middle of the air chamber. Some owners mistakenly use the cylinder balance screw to adjust engine idle, not what it is for.

Rambozo recommendation to check the coolant temp sensor is well founded. The ECU will add fuel when the engine temperature starts to run hotter than expected for a given RPM. The ECU adds fuel to enrich the fuel/air mixture to prevent a lean burn condition. This could affect the engine idle, don't know for certain but not a bad premise. Checking the calibration of the air and coolant temperature sensor is a good idea, same spec for both. Have to drain the engine coolant to remove the coolant temp sensor. A tight area to work in, but can be done.

Good luck.

[FlardaMan]

Yesterday I finished replacing all the vaccum lines and properly adjusted the throttle stop screw and readjusted the TPS to that. Today came around and I was able to balance the left and right bank properly. I just got back from the test ride to see what's changed and if the increasing idle issue persists and I can say she overall behaves 10x better. I couldn't get her over 4 bars to see if the idle would go beyond the 1k. I'll have to try again on a hotter day. But so far it seems the TPS sensor may have been my biggest culprit. Not that it was going bad but that it was tuned improperly. I'm still going to test temp sensors to make sure they are behaving properly I'm sure they are still contributing to the issue. Thank you everyone for your input. I'll update when I can properly verify the issue is solved.