Syclone dies when FP line off

[Vaders Sy]

I was checking my FP before I went to the track this past Wednesday. Pulled the line off the fuel pressure regulator and was looking at the fuel pressure gauge and the Syclone died. From memory, all my other trucks RPM's just went up and down, until I put it back on. What am I missing? It did it repeatedly, so it wasn't a fluke. My first experience with this happening.

 

[IGottaSy]

Re: Syclone dies when FP line off

Is it a stock FPR?
Old fuel filter, weak fuel pump, fuel pump wiring, leaking FPR diaphragm.

 

[Vaders Sy]

Re: Syclone dies when FP line off

New fuel pump and fuel filter. Good point about the FPR, it might be an older one from another truck that I kept.

 

[dgoodhue]

Re: Syclone dies when FP line off

Checking to see if an engine run with 9-10psi more of FP at idle isn't a official diagnostic indicator. Which one of your truck did this happen to? I would be more concerned with the stock one vs #380 with all its mods.

 

[Vaders Sy]

Re: Syclone dies when FP line off

Checking to see if an engine run with 9-10psi more of FP at idle isn't a official diagnostic indicator. Which one of your truck did this happen to? I would be more concerned with the stock one vs #380 with all its mods.

Agreed dgoodhue. I've owned a lot of these trucks, I don't recall one dying when checking the fuel pressure though. I remember the rpm's dropping, then the truck idles back up to keep itself from dying. This truck had no resistance, just dies. This was on #1385 a few mods, but stock turbo Syclone.

 

[Don W.]

Re: Syclone dies when FP line off

With engine at idle, aftermarket or stock, removing the vac line at the FPR -increases- FP. Assuming the reg is functional. What's your FP when you just turn the key on and does it hold after the pump has run for 2 seconds?

What it sounds like is when you pull the line you instantly create a big enough vac leak to kill it. Is the line plumbed to the small fitting on the back of the manifold and only goes to the FPR and MAP?

 

[Damian]

Re: Syclone dies when FP line off

It's probably throwing off the map sensor, are you plugging the line when you pull it? Mine will die if I don't cover the hose end.

 

[Don W.]

Re: Syclone dies when FP line off

It's probably throwing off the map sensor, are you plugging the line when you pull it? Mine will die if I don't cover the hose end.

Agreed. He hasn't said if it will restart either. With or without the line plugged. Mine will run with that line disconnected but I imagine some, yours obviously, don't.

 

[Vaders Sy]

Re: Syclone dies when FP line off

What's your FP when you just turn the key on and does it hold after the pump has run for 2 seconds? What it sounds like is when you pull the line you instantly create a big enough vac leak to kill it. Is the line plumbed to the small fitting on the back of the manifold and only goes to the FPR and MAP?

Hey Don! Thanks for your responses. I would have to check to see what the FP is when the key is on. I am almost positive that it is plumbed to the manifold that feeds the FPR and MAP. I'll double check. I used the Sportmachines vacuum line kit.

It's probably throwing off the map sensor, are you plugging the line when you pull it? Mine will die if I don't cover the hose end.

Yes. When I'm checking to see what the fuel pressure was without it attached is when it dies. It takes about 5 secs for it to die. I have to adjust the FPR, put the line back on for a sec for it to catches its breath, then take it back off and look at the FP again to see if I need to adjust it more. The fuel pressure was off 2 psi (41) from 43. Yours dies too? Maybe it is not a big deal then!

Agreed. He hasn't said if it will restart either. With or without the line plugged. Mine will run with that line disconnected but I imagine some, yours obviously, don't.

It will restart no problem. I do put the line back on the FPR before I start it up again.

Its probably truck by truck then. Thank you all for the help!

 

[Vaders Sy]

Re: Syclone dies when FP line off

It's probably throwing off the map sensor, are you plugging the line when you pull it? Mine will die if I don't cover the hose end.

I double checked today. It is the vacuum port off the back of the upper intake plenum. The boost gauge is teed into the FPR vacuum line as well. Nothing is teed into the MAP vacuum line.

I did not have time to check the fuel pressure with the key on and see if it holds. Getting ready for vacation, so more than likely it will have to wait.

 

[Vaders Sy]

Re: Syclone dies when FP line off

Update: I checked the fuel pressure today. Turned the key on and it holds to 42-43 lbs. After a few seconds it dropped down about 5-7 psi. If you guys aren't highly concerned, I'm moving on and I will take it as part of the truck. It is a Turbo Tweak 255 fuel pump and it seems pretty quiet compared to the walbro's I am used to using.

After my post on Eric Marshall's TT forum about my pass and other questions. He said to increase the fuel at start up. I added 3% more fuel and the Sy fired right up. I'm going to leave it sit over night and try it again. Then I'll try it after it sits for a week and see.

Going to turn the boost up a couple more lbs and I turned the alcohol on. I can start a new thread, but with the alcohol should I decrease the fuel? I read somewhere on TT forums that I should when using alcohol, it is the equivalent of adding more fuel.

The Sy is using E85.

 

[Don W.]

Re: Syclone dies when FP line off

Well the FB should hold After the pump runs for 2 two seconds. IMHO without a wide band you can't tune with alky. If you have a wide band it becomes a balancing act between fuel and alky. Your best bet, if not already done, is to wire the WB into the ECM and let Eric's chip work for you. Again just my opinion, you're gonna want to see between 11.0 to 11.3 to start at full throttle. Dial it in first then add boost. Hopefully you can also log to see how much spark the chip is pulling. That alone is the key to keeping the motor in one piece. Keep retard near -0- and add boost from there. It's like trying to balance a broomstick in you hand.

 

[Vaders Sy]

Re: Syclone dies when FP line off

Well the FB should hold After the pump runs for 2 two seconds. IMHO without a wide band you can't tune with alky. If you have a wide band it becomes a balancing act between fuel and alky. Your best bet, if not already done, is to wire the WB into the ECM and let Eric's chip work for you. Again just my opinion, you're gonna want to see between 11.0 to 11.3 to start at full throttle. Dial it in first then add boost. Hopefully you can also log to see how much spark the chip is pulling. That alone is the key to keeping the motor in one piece. Keep retard near -0- and add boost from there. It's like trying to balance a broomstick in you hand.

I'll started a new thread. Stock Turbo Syclone Second Passes but with Alcohol

I took the Sy to the track this past Wednesday using Alcohol. Feel free to check the thread out and comment.