Base fuel pressure slowly drops while riding

GXR1147 said:
Aaaaaand pump and new Parker fuel lines wasn't the issue.... smfh
Click to expand...

So when the bike is cold the fuel pressure is fine. At what point does the fuel pressure start acting up? When the bike is heat soaked? or just after the temp gauge warming up? Do you have a second fan set up on your bike?
My second fan was angled wrong, pulling all the hot air from the turbo into the bike and not ejecting it out the slit in the fairing. The result was the fuel lines reaching above 150 degrees (the max operating temp of the fmu) when the fans came on.
 
Last edited:
It seems like its "normal operating temp" on the gauge. About half way. No second fan. The FMU was mounted up top above the valve cove and is now down below the the #3 & 4 throttle body due to the ultra plenum.
 
jermzfree said:
The result was the fuel lines reaching above 150 degrees (the max operating temp of the fmu) when the fans came on.
Click to expand...

I don't see there being a big difference (if any) in tempature from the old location to the new location. I could also be completely wrong. Where did you find that max operating temp numbers and is that for all FMU's or certain model?
 
Once it started to got up to temp, I check the fuel pressure and it was starting to drop. Also notice how when the rpms are raised, the pressure doesn't ride at all like in the other video. I contributed to let it run to watch the voltage and pressure but by the time it got to 26 psi and I tried to blip the throttle it died.
 
So we now know the symptoms. Go to test the generator/stator. It is out of spec when up to temp. Next I'm gonna test the regulator/rectifier as well.

IMG_7280.JPG


IMG_7281.JPG
 
Ima need some ones opinion here. So, testing the regulator/rectifier, on the chart anything that gives a range (.4-.7 & .5-1.2) is spot in the middle of that range, but on all the other "approx 1.5" I get nothing. This is also being checked with a Fluke 87.V.

IMG_7282.JPG


IMG_7283.JPG
 
So at this point it has a new battery and regulator/rectifier. Figured the R/Rvthat was on it was original and gonna leave me stranded some time in the future so I went with that first. While that didn't fix the issue with not charging after the bike is warm, it was a great improvement in charging at idle. The factory R/R was only putting 13.4v (at best) at idle and required racing to get it into the 14's, the new one from Frank is giving a steady 14.4V at idle and when reved. A looking at the stator closely I found some things that I didn't like the looks of and have a new one, also from frank, on the way. Guessin it will be here late today (I'm like the last stop for the post office). So I should have it in tomorrow. I'll post some pics of the old one later today. Before I ordered the stator, I looked at the wire schematic and verified there is nothing between the R/R and stator and ohmed out those wires and connectors. Which I have .1 ohms as the highest reading. So those wires are good as well.
 
Stator removed. Looks like it has gotten a little warm. Some spots the insulation on wires is just brittle and falling apart. The coating on the windings is startinto burn through in a couple spots. Bla bla bla. It doesn't look healthy in my inexperienced opinion

IMG_7349.JPG


IMG_7350.JPG


IMG_7351.JPG


IMG_7352.JPG


IMG_7353.JPG
 
ali123 said:
long island is nice this time of year
Click to expand...
Haha, I was just up there in march iirc. It was snowing on the way back. F that drive up there and back in the same day. Frank was kind enough to work with me and tune it while I waited and I was able to bring it back ye same day.
 
Oh, just now saw this .... the readings in the manual are based on the Suzuki test tool not a typical good tester. Carefully check all of your connections, I've seen some very strange things because the connections were corroded. Recently, my nitrous race bike started to show sign of not charging, the battery voltage would drop while at idle. Checked with the manual and found nothing. Went back and checked/cleaned all the connections with high grit sand paper...and like magic everything starting working just fine.
 
RansomT said:
Oh, just now saw this .... the readings in the manual are based on the Suzuki test tool not a typical good tester. Carefully check all of your connections, I've seen some very strange things because the connections were corroded. Recently, my nitrous race bike started to show sign of not charging, the battery voltage would drop while at idle. Checked with the manual and found nothing. Went back and checked/cleaned all the connections with high grit sand paper...and like magic everything starting working just fine.
Click to expand...
I did that also, pulled ground wires and cleaned contacts ect. Ohmed out connections as well. I basically tried not to spend money first.
 
SOLVED!!!! (I think/hope)
Tomorrow's test ride will confirm. Replaced the stator today and fired it up. Charging like normal at idle and when the fan kicked on, the fuel pressure maintained its set point. Continued to run it until the fan kicked off and a few seconds later was able to get 14.3v out of the battery again. That old stator checked out OK by Suzuki's tests in the factory manual, yet clearly wasn't up to the task. If tomorrow's test ride goes well she'll get a bath afterwards and I get to start trying to get used to the new 100hp it got over the winter. (Did I mention Frank @ Powerhouse is the man?)
 
You must log in or register to reply here.

Similar threads

Quiksilver
dropping fuel pressure after priming.
Replies
4
Views
1,512
Quiksilver
Quiksilver
texas-buzzard
high fuel pressure
2
Replies
21
Views
3,388
Ryan Schnitz
Ryan Schnitz
C
Fuel Pressure Fluctuations
Replies
14
Views
5,188
cocoaspud
C
mike miller
Fuel pressure issue
Replies
5
Views
1,629
mike miller
mike miller
3gturbo
fuel pressure issue
Replies
3
Views
1,022
Cecil_Stringer
C
Back
Top