ECU for 1981 GPZ 1100 EFI - Any Way to Check it Ou

Hi

Never had a FI related problem with my B1. It's a low miler, but no problems since 2004, when i bought it.

My approach to old stuff is to keep them as original as possible. No way of converting it to carbs! what make interesting these bikes is being FI in these years and, just my opinion.

I tend to agree with the folks saying that maybe is not a ECU related problem. I'd suspect of connectors or sensors. I've got the Clymer and they mention several tests to check ECU and sensors.

Regarding TPS... the B1 has not the modern (and cheap) approach of calculating air suctioned by the engine (TPS); it got an air flow meter, much more precise for fuel calculation. These system being crude? no way! i think it is pretty advanced for it's time. My B1 pulls like a train, when i start-up her and with stone-cold engine and take the fast-idle off, she idles at 100-200RPM. Wonderful bike, i'll never sell it.

I strongly reccomen d you to get the Clymer, it was worth 100 times what i paid for it when i restored my bike.

Hi

Never had a FI related problem with my B1. It's a low miler, but no problems since 2004, when i bought it.

My approach to old stuff is to keep them as original as possible. No way of converting it to carbs! what make interesting these bikes is being FI in these years and, just my opinion.

I tend to agree with the folks saying that maybe is not a ECU problem. I'd suspect of connectors or sensors. I've got the Clymer and they mention lots of tests for ECU and sensors.

Regarding TPS... the B1 has not the modern (and cheap) approach of calculating air suctioned by the engine (TPS); it got an air flow meter, much more precise for fuel calculation. These system being crude? no way! i think it is pretty advanced for it's time. My B1 pulls like a train, when i start-up her and with stone-cold engine and take the fast-idle off, she idles at 100-200RPM. Wonderful bike, i'll never sell it.

I strongly reccomen d you to get the Clymer, it was worth 100 times what i paid for it when i restored my bike.

Hi Everyone:

Firstly, let me thank you for all for the feedback, it's much appreciated.

Well, I went through the bike thoroughly, checking electrical items, cleaning connections and grounds, and found a bad coil. I replaced it with a set of green Dyna coils and Dyna wires, and thought all would be good. I got it back together today, and fired it up, and it's running just as bad as when I brought it home two weeks ago. It barely runs, acts like its lean as can be, will only rev above 3.5K RPM, and that's the best she'll do.

Before I fired it up today, I also put in new spark plugs, flushed the fuel system (new filter too), fully charged the battery, checked valve clearances, and changed vacuum lines.
FI's idle and throttle switches checked out all right as did the ignition's pick up coils. I verified the timing was all right with a timing light when the bike was running too. Performed compression checks on it too - around 150PSI for all cylinders.

I found an old posting on gpz1100ownersgroup forum about a guy who was having similar problems and traced it to a bad igniter. I checked mine (guess I wasn't all that thorough after all) today after reading this. Doing resistance checks per the factory service manual. It checked out all right except one. The normal maximum for one test was 700 Ohms, but my igniter registered 900 Ohms.

Does anyone think that this 200 Ohms over the standard max of 700 Ohms is significant enough to say that the igniter is bad and MAY be the source of my problems?

Again, thanks in advance for your help.

Marty

I think I just replied to your email GPZ1100_Rider.

If you have the 3-ohm green coils already, then you might want to try a Dyna S ignition, if that's even an option on the fuel injected bikes. If you go with the stock ignition (or HEI mod), you will probably want the grey 2.2 ohm coils.

(Does the FI talk to the ignition?)

First place to start with any fuel injection system is the fuel filter. [knowing the engine is in proper tune]

Follow that with checking the air filter.

Check for cracked vacuum lines, especially leading to the fuel pressure regulator.

Check and clean all grounds for the DFI harness.

Ground the engine temperature wire. See if that cures the stumble.

It could be a gummed up injector that's dribbling fuel at low demand rpm. You can never go wrong to have the injectors cleaned.

Knowing the injectors are in working order when you have problems only makes everything else easier and more logical to diagnose. That's especially true with that model because of age and the location of the injectors.

It's also always in your best interests to know you don't have any tight valve clearances. If you did happen to have one, or more, no EFI diagnostic efforts will uncover it.

So the point is this. If you check the obvious/easy items and find nothing wrong, it would be a good idea to perform a routine tune up, followed by an inspection of the injector spray pattern, then proceed from there with the factory diagnostic process.

I worked on all the GPz models from 81 through 87 on a daily basis. ECU failures were uncommon. The last one I replaced was on an 83 model and it showed no diagnostic code flashing. The bike would simply start missing after ridden for about 30 minutes. As a last resort we swapped the ECU and it solved the problem.

I still have that ECU :laugh:

Larry:

Thanks for the advice. I haven't tried grounding the engine temp wire.

Would a gummed up injector that dribbles cause it to act like described?

When you pull the injectors for cleaning, do you also replace the high pressure hoses and clamps? Mine look fine.

Good to hear that the failure rate of ECU's are in my favor.

Marty

Lou:

Got your replies. Thanks. Z1 Enterprises has a Dyna 3 ignition for my bike. I'm assuming that it eliminates the stock igniter. Anyone know this? And has anyone any experience with the Dyna 3 Ignition?

Thanks.
Marty

Dyna III replaces the pickups and rotor (but not the entire advancer) and module. I have one for the 550. It works basically the same as the Dyna S, but uses an external module of its own. It uses the 3-ohm coils you already have.