LT-1 issue

John Nechiporchik · 04-12-2015, 07:41 AM

Fired up LT-1 after rebuild and all appeared to be well. At initial start up, only ran the engine to around 2500RPM.
Loaded up and went to track.
At track, warmed up and drove to tech and back to trailer. went to 3000and all was well
After adding fuel to cell and a quart of trans fluid, headed to lanes. Car would not accelerate driving to lanes, headed back to trailer.
As it sits now, car will start, idle, and immediately stumble as the throttle is opened...like it is not getting fuel.
Gas was a new sealed container of renegade 110+
Fuel map same as last year
Rebuild included new rings, bearings, cam, valve springs and a different set of heads.
Before initial start, I flushed the fuel system and replaced the fuel filter.
Looking for possible causes.
Bad fuel?
Throttle position sensor?
Any ideas??
Thanks for any help.

John

Mike Savelle · 04-12-2015, 08:28 AM

what was the fuel pressure at ?

Jon Sarrett · 04-12-2015, 08:58 AM

You didn't mention anything about timing. Have you checked it? If so, where is it?

What engine management system are you using?

John Nechiporchik · 04-12-2015, 09:43 AM

Fuel pressure at 45psi. We did notice that the fuel pressure gauge seemed to drop more quickly once the engine was shut off. Typically, the reading on the gauge very slowly declines after shut off of system.
The timing is set at 42 degrees and I have an old style Accel Cal Map system.

Thanks.

ss3011 · 04-12-2015, 09:55 AM

Make sure the MAP sensor wiring, and sensor is OK. If you removed the sensor, from last year, make sure the seal to the intake is in good condition.

John Nechiporchik · 04-12-2015, 10:38 AM

I'll check that . I did remove it since last year.

Jim Whitehead · 04-12-2015, 12:13 PM

Use a OHMS meter and sweep test the TPS sensor.

Alan Roehrich · 04-12-2015, 02:29 PM

If the fuel pressure drops fairly soon and/or quickly after you shut the vehicle off, you need to test fuel pressure and volume, as well as determine whether or not the fuel pump used has a check valve. If fuel pressure did not drop when the car ran before, but does now, I suspect the pump is supposed to have a check valve, and there is now a problem.

Dyno · 04-12-2015, 02:50 PM

Broken ignition rotor.

John Nechiporchik · 04-12-2015, 03:12 PM

Dyno, Brand new MSDcap and rotor.
Alan, How would a faulty check valve in the pump react?
Will check the TPS for sweep again. Checked it in the fall and it was OK.

Re-terminated 3 TPS leads as the old terminals seemed loose. This did not solve problem. Also pulled back timing to 36......no difference.

04-12-2015, 07:41 AM	#1
John Nechiporchik Member Join Date: Mar 2007 Location: Grosse Ile Mi. Posts: 315 Likes: 74 Liked 12 Times in 6 Posts	LT-1 issue Fired up LT-1 after rebuild and all appeared to be well. At initial start up, only ran the engine to around 2500RPM. Loaded up and went to track. At track, warmed up and drove to tech and back to trailer. went to 3000and all was well After adding fuel to cell and a quart of trans fluid, headed to lanes. Car would not accelerate driving to lanes, headed back to trailer. As it sits now, car will start, idle, and immediately stumble as the throttle is opened...like it is not getting fuel. Gas was a new sealed container of renegade 110+ Fuel map same as last year Rebuild included new rings, bearings, cam, valve springs and a different set of heads. Before initial start, I flushed the fuel system and replaced the fuel filter. Looking for possible causes. Bad fuel? Throttle position sensor? Any ideas?? Thanks for any help. John

04-12-2015, 08:28 AM	#2
Mike Savelle Member Join Date: Dec 2001 Location: Ontario Canada Posts: 358 Likes: 100 Liked 6 Times in 4 Posts	Re: LT-1 issue what was the fuel pressure at ?

04-12-2015, 08:58 AM	#3
Jon Sarrett Member Join Date: Mar 2002 Location: Sullivan, OH Posts: 302 Likes: 660 Liked 136 Times in 43 Posts	Re: LT-1 issue You didn't mention anything about timing. Have you checked it? If so, where is it? What engine management system are you using?

04-12-2015, 09:43 AM	#4
John Nechiporchik Member Join Date: Mar 2007 Location: Grosse Ile Mi. Posts: 315 Likes: 74 Liked 12 Times in 6 Posts	Re: LT-1 issue Fuel pressure at 45psi. We did notice that the fuel pressure gauge seemed to drop more quickly once the engine was shut off. Typically, the reading on the gauge very slowly declines after shut off of system. The timing is set at 42 degrees and I have an old style Accel Cal Map system. Thanks.

04-12-2015, 09:55 AM	#5
ss3011 Senior Member Join Date: Feb 2002 Location: Southeast Michigan Posts: 885 Likes: 63 Liked 221 Times in 102 Posts	Re: LT-1 issue Make sure the MAP sensor wiring, and sensor is OK. If you removed the sensor, from last year, make sure the seal to the intake is in good condition.

04-12-2015, 10:38 AM	#6
John Nechiporchik Member Join Date: Mar 2007 Location: Grosse Ile Mi. Posts: 315 Likes: 74 Liked 12 Times in 6 Posts	Re: LT-1 issue I'll check that . I did remove it since last year.

04-12-2015, 12:13 PM	#7
Jim Whitehead Member Join Date: Mar 2003 Location: MA. Posts: 276 Likes: 128 Liked 145 Times in 38 Posts	Re: LT-1 issue Use a OHMS meter and sweep test the TPS sensor.

04-12-2015, 02:29 PM	#8
Alan Roehrich VIP Member Join Date: May 2006 Location: Murfreesboro TN Posts: 4,905 Likes: 992 Liked 1,030 Times in 269 Posts	Re: LT-1 issue If the fuel pressure drops fairly soon and/or quickly after you shut the vehicle off, you need to test fuel pressure and volume, as well as determine whether or not the fuel pump used has a check valve. If fuel pressure did not drop when the car ran before, but does now, I suspect the pump is supposed to have a check valve, and there is now a problem. __________________ Alan Roehrich 212A G/S

04-12-2015, 02:50 PM	#9
Dyno Senior Member Join Date: Dec 2002 Posts: 869 Likes: 916 Liked 604 Times in 177 Posts	Re: LT-1 issue Broken ignition rotor.

04-12-2015, 03:12 PM	#10
John Nechiporchik Member Join Date: Mar 2007 Location: Grosse Ile Mi. Posts: 315 Likes: 74 Liked 12 Times in 6 Posts	Re: LT-1 issue Dyno, Brand new MSDcap and rotor. Alan, How would a faulty check valve in the pump react? Will check the TPS for sweep again. Checked it in the fall and it was OK. Re-terminated 3 TPS leads as the old terminals seemed loose. This did not solve problem. Also pulled back timing to 36......no difference.

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