2001 gti starts on trailer and not in the water

[Cheflen]

I finally got a pop off test, it was around 20 psi, it's supposed to be between 36 and 40. So it is flodding not allowing me to start it. I have tried adjusting the pop off but I can't get it above 35, I have bent the arm and changed the spring but I can't get the pop off any higher, does anybody know why?

 

[kmarts]

I finally got a pop off test, it was around 20 psi, it's supposed to be between 36 and 40. So it is flodding not allowing me to start it. I have tried adjusting the pop off but I can't get it above 35, I have bent the arm and changed the spring but I can't get the pop off any higher, does anybody know why?

Well there's only a few things that will affect your pop off pressure...

Spring
Arm adjustment
Valve seat diameter

Also make sure you're lubing the needle and seat with WD-40 and testing multiple times for consistency.

 

[Cheflen]

Well there's only a few things that will affect your pop off pressure...

Spring
Arm adjustment
Valve seat diameter

Also make sure you're lubing the needle and seat with WD-40 and testing multiple times for consistency.

DO you think I will still have hard starting with a pop off of 35?

 

[kmarts]

DO you think I will still have hard starting with a pop off of 35?

Good question. Iow pop off will def make it run rich. Your needles may be leaking too. Regardless you need to have it in spec to rule it out.

You only have 1mm adjustment on the arm, go more then that and you'll have problems. It should be flush with the pump body.


And also pressurize your assembled carb (like 10psi) after youre done and make sure it holds air, if not you have a problem.

With all new mikuni parts on my carbs pop off was 30 psi (chart said it should be 33) so I'm at the upper end. I had problems starting before but it was from a leaking crank seal which currently has my engine on the garage floor lol.

 

[Cheflen]

Well it has a brand new needle and seat so I hope it's not that, I cleaned up the whole area around the needle and seat but I'm just not sure what to do, I think I definitely bent the arm a little farther than 1 mm but I got the end to be flush with the carb body

 

[Cheflen]

Good question. Iow pop off will def make it run rich. Your needles may be leaking too. Regardless you need to have it in spec to rule it out.

You only have 1mm adjustment on the arm, go more then that and you'll have problems. It should be flush with the pump body.


And also pressurize your assembled carb (like 10psi) after youre done and make sure it holds air, if not you have a problem.

With all new mikuni parts on my carbs pop off was 30 psi (chart said it should be 33) so I'm at the upper end. I had problems starting before but it was from a leaking crank seal which currently has my engine on the garage floor lol.

I also hope it's not leaking crank seals because I just put a new crank in there, it starts up fine for the first start in the water but after it's run and has fuel pressure built up it doesn't want to start as easily. That's why I'm hoping it's just pop off since it was at 20 psi

 

[greenhornet2]

have you run it in the water since the pop off is now at 35psi?

 

[Cheflen]

have you run it in the water since the pop off is now at 35psi?

Not yet I am tomorrow, I wanted to check to see if it won't give me starting issues because I Would like to be able to just ride for the last month of summer instead of having to pull this thing apart every week

 

[kmarts]

I also hope it's not leaking crank seals because I just put a new crank in there, it starts up fine for the first start in the water but after it's run and has fuel pressure built up it doesn't want to start as easily. That's why I'm hoping it's just pop off since it was at 20 psi

Yeah I had read that you put new outters on I doubt that's the problem... mine on the trailer wouldn't rev down if you blipped the throttle. On the water it fell on its face if you touched the gas from idle. The hard starting was from it being too lean, always needed choke.

Also, make sure your assembled carbs hold air.

Kids have basbeball the next two days so hopefully I'll have her done by the weekend.

Good luck

 

[Cheflen]

Yeah I had read that you put new outters on I doubt that's the problem... mine on the trailer wouldn't rev down if you blipped the throttle. On the water it fell on its face if you touched the gas from idle. The hard starting was from it being too lean, always needed choke.

Also, make sure your assembled carbs hold air.

Kids have basbeball the next two days so hopefully I'll have her done by the weekend.

Good luck

Yeah luckily it runs great as soon as it starts. It's just flooding. I'll have to check that the carbs hold air, it's 10 psi going into the fuel in line while the return and pulse line are plugged, right?

 

[mikidymac]

Yes,

 

[Cheflen]

So I assembled my carb, it held air. Installed the carb and everything else and so far it fires first crank each time. Water test is tomorrow

 

[Cheflen]

After the water test it would cut out whenever I gave it throttle and it sounded like it was misfiring and after running it was hard to start so I'm stumped

 

[Mekanix]

What's the compression now ?
That 138psi is still really suspicious to me for essentially a refreshed topend. I mean every top end I've done resulted in 155-160psi right away and settle somewhere in the middle but I'm at sea level too so that helps the numbers.

Is it backfiring through the carb or out through the exhaust?
Seems like your higher pop off might be way too lean and the carb being rich before was making up for something else maybe?
The reason you couldn't get a high enough pop off before wasn't the arm or spring. It was the carb body where the spring goes into that is worn a little. So the spring sinks a little deeper and you have less spring pressure.


I've also seen many shear the woodruff key on the crank and retard the ignition just enough to make it backfire like you said and hard to start.

 

[Cheflen]

What's the compression now ?
That 138psi is still really suspicious to me for essentially a refreshed topend. I mean every top end I've done resulted in 155-160psi right away and settle somewhere in the middle but I'm at sea level too so that helps the numbers.

Is it backfiring through the carb or out through the exhaust?
Seems like your higher pop off might be way too lean and the carb being rich before was making up for something else maybe?
The reason you couldn't get a high enough pop off before wasn't the arm or spring. It was the carb body where the spring goes into that is worn a little. So the spring sinks a little deeper and you have less spring pressure.


I've also seen many shear the woodruff key on the crank and retard the ignition just enough to make it backfire like you said and hard to start.

I can see how it can be way too lean, but I know the compression numbers are good for 2 reasons. 1, I didn't do a proper compression test as I had the throttle closed during the test and 2, was a few days ago before I adjusted my pop off I only had a hard starting condition, but once the ski was started it ran perfectly fine, no hesitations with the throttle and would have full power so the compression is there

 

[Bill-H]

Could you re-run the compression test, to satisfy us all on the numbers??

Seems easier than having speculation.

 

[Cheflen]

Could you re-run the compression test, to satisfy us all on the numbers??

Seems easier than having speculation.

I don't have a compression tester and I had to go through a long process to borrow one. But I am saying that I don't believe there is anything wrong with the compression, it has full power it would rev up very quickly even with two riders.