No reving under pressure

[Tomchri]

Late last fall she wasn't interested in reving all the way, but not every time ? Soon winther, check then.

She still had the PC 3.

Finally had the CO set at 0, valves 15 - 20 , air 1 turn out, Omron relays, new fuel filter, set the tps 157, new sensor for the timing.

Running perfect idling ( she is balanced ) she sounded perfect just reving, but under pressure, only sneezing and no go.

Tried another TPS, she was much better up to 3500 - 4, could run for about 25min with no issues, but still not interested in higher rpm, and then she was getting worse and worse, barely made it home.

Someone had some issues with the PC,,,, time to take it of. Why would someone cut the cables so close to the connector

[LowRyter]

sneezing?  Could it be the fuel filter?

[paulnaz]

  Tomchri, I would check the coils and plug wires for proper resistance, if they're bad, they don't do well under load.

        

     Paul B

[JBBenson]

TPS @150mV with:

 

1.

Throttle adjustment screws backed off?

2.

Choke/fast idle cable disconnected?

3.

Throttle connecting rod disconnected?

 

Double check. Your symptoms sound like classic TPS out-of-whack issues.

[Pressureangle]

My '97 Sport Injected did that while the cam sensor was failing, including feeling a bit better with a new TPS. Then the sensor went completely dead.

If it gets worse with heat, and comes back when cold, perform a resistance check on the cam sensor when cold and hot, check that it's not shorting or opening with the heat. Mine was swollen and hard even to pull from the case.

[Tomchri]

Fuel filter new, cam sensor new, tps properly adjusted, just heard from another guy over here, he had problems with the plug wires,,,,,  will check that next week.

thanks for any advice.

cheers tom

[Pressureangle]

Re-reading your original post, considering everything, it seems obvious this was a problem in the past with wires cut. Time sensitivity usually means a heat problem, and heat problems are most often a high-resistance connection that is marginal when cold and passes into failure as it heats. Also, the ground path is overlooked, and reports are that MG made very poor choices with ground circuits. Although I performed more than one change at once, grounding my instruments/fairing bracket/frame/engine all together made everything smoother. You may investigate the ECU ground, the engine to frame and engine to battery grounds as potential trouble spots. 

 

[Tomchri]

Pressureangle

Small report, had a little time late yesterday, did see that both of the spark plugs, that thing on the treads were both loose. That can make a problem. 

Ok, lets try, a little slow starting, but perfect idling and good respone snapping the trottle.   But after 300yards, turn around.     Took the plugs out, wish I could send a picture,,,,,   Way to lean.   She is not getting enough fuel...

Extra ground from ECU to battery, extra from regulator to frame.  Did I have an internal leak from the fuel pump ? but she is steady on the pressure,,,, is the pressure high enough ? Are my injectors  under the influence ? 

Will check wires for resistance, will find out about coils..    Is it my ECU.

cheers tom                                                 

[Lucky Phil]

Pressureangle

Small report, had a little time late yesterday, did see that both of the spark plugs, that thing on the treads were both loose. That can make a problem. 

Ok, lets try, a little slow starting, but perfect idling and good respone snapping the trottle.   But after 300yards, turn around.     Took the plugs out, wish I could send a picture,,,,,   Way to lean.   She is not getting enough fuel...

Extra ground from ECU to battery, extra from regulator to frame.  Did I have an internal leak from the fuel pump ? but she is steady on the pressure,,,, is the pressure high enough ? Are my injectors  under the influence ? 

Will check wires for resistance, will find out about coils..    Is it my ECU.

cheers tom                                                 

fuel pump,regulator, collapsed fuel hose internally. Is the filter installed the right way around?

 

Ciao  

[Pressureangle]

How about as simple as your fuel petcock is partially blocked, closed, or for some reason failing to deliver enough fuel at load? You've checked the pressure, but you probably aren't able to check it while riding. 

[Tomchri]

Plugwires with cap 4.73 and 5.11 ohm , testing the coils ? , out with fuel pump,,, Do I like those plastisc connectors for the fuel lines , NO, filter right way, there isnt exactly a petcock, just the line from the pump.

My pressure fuelline goes to the left injector ,,,,,, hm is that correct, or should it go to the right ?? Does it matter. I'll take the blame.

Since I did the clutch last year, most of the bolts had been loosened and tightened concerning ground.

Cheers Tom

[Lucky Phil]

Plugwires with cap 4.73 and 5.11 ohm , testing the coils ? , out with fuel pump,,, Do I like those plastisc connectors for the fuel lines , NO, filter right way, there isnt exactly a petcock, just the line from the pump.

My pressure fuelline goes to the left injector ,,,,,, hm is that correct, or should it go to the right ?? Does it matter. I'll take the blame.

Since I did the clutch last year, most of the bolts had been loosened and tightened concerning ground.

Cheers Tom

You need to do a fuel pressure check. Its a hassle but the components you need arent expensive to make up a test tool. Really everyone that runs modern EFI systems and wants to do home maintenance should have one these days, its part of the basic equipment needed.

It doesnt matter which way the fuel lines run, whatever uses the least amount of hose and has the simplest routing. Mine does left first then right then reg back into tank.

If the fuel pressure is low then the engine will often idle and rev fine unloaded but fall on its face when you try and ride it.

 

Edit..... I just reread your first post......hows the timing sensor gap? Did you check it when you replaced the sensor?

 

 

Ciao

[Tomchri]

Did measure the sensors = same, and there was 2 shims. Put in new o ring,,  in the space for it in the  block. Probably shoud have done the correct measure,,  something, a hole or something visible on gear wheel when turning the motor?

If I put a fuel gauge on the pressure line, to see the build up pressure to ex amount in so and so long time , how much is recomended.   Thats one thing, seeing the pressure under load is another.

The screen under the pump , could hurt the suction ?        Started the pump on the bench,,,  sounded healty,, doesent mean a lot.    Spark plugs say Lean.

Thanks for trying to help.

Cheers tom.

[Chuck]

 You can measure from the flat the sensor sits on to a tooth on the phonic wheel. Should have .030" clearance. I'm certainly no expert here, but as far as I know.. pressure = pressure. I *think* 40-45 PSI. Sure, if the screen is clogged it could hurt suction.

[Lucky Phil]

 You can measure from the flat the sensor sits on to a tooth on the phonic wheel. Should have .030" clearance. I'm certainly no expert here, but as far as I know.. pressure = pressure. I *think* 40-45 PSI. Sure, if the screen is clogged it could hurt suction.

Yes Chuck spot on on all counts, most systems work on 3.5bar. You can rig up a system with extended hoses and tape the gauge to the tank and ride it to check it under load. Sounds dodgy but one trip around the block will tell you if there's an isssue. If your bike has the in tank pump which I believe it does its worth checking the screen.  

 

Ciao