HELP!! LT1 runs great, but won't start! - The 1947 - Present Chevrolet & GMC Truck Message Board Network

70cst10 · 06-21-2003, 08:43 PM

Hi. I finally got the lt1 in my truck fired up today. The only problem is, it won't start without some starting fluid in the intake. It runs great after that. It idles perfect and roars like a beast with throttle. What could the problem be? It seems like the injectors don't turn on until after the motor starts. I don't know where to look for this..

krue · 06-21-2003, 09:00 PM

Make sure your fuel pump is starting as soon as you turn the key on. Other than that I can't help.

cableguy0 · 06-21-2003, 09:06 PM

really dumb question and i dont mean to insult you but are you a running a mechanical or an electric fuel pump. but other than that if the pump is electric like it has to be make sure it is wired to have power when the key is on not just after the engine is running. did u use the stock harness get a custom modify it or what? the more info u can give the more we can help ya

70cst10 · 06-21-2003, 09:10 PM

I've got the camaro pump (electric) in a new aluminum fuel cell. It pu,ps fine and primes the system when the key comes on. It just won't fire without starting fluid. I don't get it. Could it have something to do with the brake switch? I didn't use the switch from the camaro, and I noticed it powers the pcm for something..

Project1970 · 06-21-2003, 09:48 PM

I don't think so...

I don't know enough of the LT1 off the top of my head to remember if there's any sort of cold-start injector or anything. It sounds like whatever is supposed to prime it is just not doing its job. Try some Camaro or Corvette boards...

**68 Stepside** · 06-21-2003, 10:07 PM

The 97 T/A we had in auto shop had a similar problem. We had to put our hand over the air inlet to start it after it had been sitting for about a year not running. After we ran it for a while, the problem went away, but I can't guarantee it'll help you out....just something to think about.

Good luck, and keep us posted.

Mike C · 06-21-2003, 10:12 PM

Make sure that the fuel pump and ignition are both getting 12v DURING cranking. I had a crappy Accel electronic ignition that would only fire when you let off the key from cranking. Dumped that POS.

ddsmith · 06-21-2003, 10:26 PM

I vote for a cold start injector. It is suppose to inject gas for startup only. If it is not functioning then you would experience this type of problem.

jay-dawg · 06-22-2003, 03:25 AM

Congratulations, glad to hear you are in the final stages of your engine swap. Hope the problem clears. BTW, which company did you go with for your gas tank.

sgtjed · 06-22-2003, 03:43 AM

might ask these guys here under the hybrid part of the forums.

http://lt1tech.com/

jay-dawg · 06-22-2003, 11:26 AM

linky no worky.

Smooth68 · 06-22-2003, 11:45 AM

looks to be correct link, site just appears to be down.

70cst10 · 06-22-2003, 12:28 PM

I had a friend make the tank for me. He did an awesome job and didn't charge me anything.

I'll try covering up the air intake and see if that helps. Another thing I noticed is the fuel pump is only pumping about 35psi. I have a manual that says it should be regulated between 41 and 47psi. Could this be the problem? I don't get why the motor runs so great, but won't start. It seems like it's getting enough fuel running.

Project1970 · 06-22-2003, 12:57 PM

I believe 35 is low...it's definitely a fuel delivery problem of some sort, and that probably isn't helping. I'd also look into the possibility of a clogged injector...I did a bit of research and it looks like LT1's don't have a cold start injector (tuned-ports got rid of them in 1989 or so).

Did you run a new feed line from the tank to the engine? I believe the stock line is only appropriate for a return and can't cut it for feed...

70cst10 · 06-22-2003, 02:22 PM

Well, we got it running. It turns out, the direction of air flow through the MAF is pretty important. duh... It runs awesome now, and it fires up on the first or second turn (hot or cold). There's still a bit of small stuff that needs to be finished. I'll probably be driving it next weekend.

sgtjed · 06-22-2003, 03:06 PM

cool ya got it fixed,the website i posted is down at the moment it seems,but they have some good stuff there.

Blackhawkdc · 06-22-2003, 07:38 PM

check your fuel pressure regulator

06-21-2003, 08:43 PM	#1
70cst10 Senior Member Join Date: Jun 2001 Location: Gaston, SC Posts: 580	HELP!! LT1 runs great, but won't start! Hi. I finally got the lt1 in my truck fired up today. The only problem is, it won't start without some starting fluid in the intake. It runs great after that. It idles perfect and roars like a beast with throttle. What could the problem be? It seems like the injectors don't turn on until after the motor starts. I don't know where to look for this.. __________________ Milan 1964 Chevelle SS 283/M20

06-21-2003, 09:00 PM	#2
krue Designated A-hole! Join Date: Mar 2003 Location: South Mississippi Posts: 36,448	Make sure your fuel pump is starting as soon as you turn the key on. Other than that I can't help. __________________ "If it ain't broke, fix it 'til it is!" Being stupid ain't illegal. We're Still Debt Free Except for the House!!! www.daveramsey.com 70 GMC SWB Stepside project "Green Booger" soon to be 6.0l/4l80e 93 S-10 "Poppaw's Truck"

06-21-2003, 09:06 PM	#3
cableguy0 Senior Member Join Date: Apr 2000 Location: Delta,Pa Posts: 14,948	really dumb question and i dont mean to insult you but are you a running a mechanical or an electric fuel pump. but other than that if the pump is electric like it has to be make sure it is wired to have power when the key is on not just after the engine is running. did u use the stock harness get a custom modify it or what? the more info u can give the more we can help ya __________________ Owner of North Point Car Care in Dundalk Md. We specialize in custom exhaust on both modern and classic vehicles. We are a full service auto shop from classics to modern vehicles. Feel free to contact me with questions. I will give a 10% discount to any board member.

06-21-2003, 09:10 PM	#4
70cst10 Senior Member Join Date: Jun 2001 Location: Gaston, SC Posts: 580	I've got the camaro pump (electric) in a new aluminum fuel cell. It pu,ps fine and primes the system when the key comes on. It just won't fire without starting fluid. I don't get it. Could it have something to do with the brake switch? I didn't use the switch from the camaro, and I noticed it powers the pcm for something.. __________________ Milan 1964 Chevelle SS 283/M20

06-21-2003, 09:48 PM	#5
Project1970 14.1 @ 96MPH Join Date: Jul 2001 Location: Mesa, AZ Posts: 2,811	I don't think so... I don't know enough of the LT1 off the top of my head to remember if there's any sort of cold-start injector or anything. It sounds like whatever is supposed to prime it is just not doing its job. Try some Camaro or Corvette boards... __________________ Project1970 - LS1 Swap Complete!

06-21-2003, 10:07 PM	#6
68 Stepside huh? Join Date: May 2000 Location: Washington, Illinois Posts: 5,690	The 97 T/A we had in auto shop had a similar problem. We had to put our hand over the air inlet to start it after it had been sitting for about a year not running. After we ran it for a while, the problem went away, but I can't guarantee it'll help you out....just something to think about. Good luck, and keep us posted. __________________ Someday when I'm lonely, Wishing you weren't so far away, Then I will remember Things we said today. RIP El Jay

06-21-2003, 10:12 PM	#7
Mike C Registered User Join Date: Dec 1999 Location: Austin, TX, USA Posts: 7,738	Make sure that the fuel pump and ignition are both getting 12v DURING cranking. I had a crappy Accel electronic ignition that would only fire when you let off the key from cranking. Dumped that POS. __________________ 44 Willys MB 52 M38A1 64 Corvette Coupe 68 Camaro 'vert LT1 & TH700 69 Z/28 355 12.6's @110 69 Chevy Short Step 4 1/2"/7" drop 72 Jimmy 4WD 4spd 4" & 35's 02 GMC 2500HD 4x4 Duramax

06-21-2003, 10:26 PM	#8
ddsmith Glowing since 1978 Join Date: Mar 2001 Location: Lusby,MD,USA Posts: 532	I vote for a cold start injector. It is suppose to inject gas for startup only. If it is not functioning then you would experience this type of problem. __________________ 66 Chevy C30 Stakebody Dump, PS,PB, 327cu in 71 Corvette Coupe 454 4 speed 69 Chevy C20 Custom Camper

06-22-2003, 03:25 AM	#9
jay-dawg chevelito Join Date: Jun 2001 Location: Honolulu, HI USA Posts: 1,609	Congratulations, glad to hear you are in the final stages of your engine swap. Hope the problem clears. BTW, which company did you go with for your gas tank. __________________ New deadline...when my son can drive. Aloha from Honolulu, HI

06-22-2003, 03:43 AM	#10
sgtjed What if? Join Date: Oct 2002 Location: Choctaw,Oklahoma Posts: 649	might ask these guys here under the hybrid part of the forums. http://lt1tech.com/ __________________ 2002 red extended cab Silverado 2002 Wheatland yellow Suburban

06-22-2003, 11:26 AM	#11
jay-dawg chevelito Join Date: Jun 2001 Location: Honolulu, HI USA Posts: 1,609	linky no worky. __________________ New deadline...when my son can drive. Aloha from Honolulu, HI

06-22-2003, 11:45 AM	#12
Smooth68 Registered User Join Date: Aug 2001 Location: West Fork, Arkansas - Razorback Country Posts: 1,826	looks to be correct link, site just appears to be down. __________________ Smooth68's Web Site WTB 64-66 project or frame/cab, SWB or LWB...I have the fever! Whatcha got?? '68 Short Step - Shaved Body, Soon Bagged - *SOLD* Driver-2004 GMC Z-71 Ext-cab

06-22-2003, 12:28 PM	#13
70cst10 Senior Member Join Date: Jun 2001 Location: Gaston, SC Posts: 580	I had a friend make the tank for me. He did an awesome job and didn't charge me anything. I'll try covering up the air intake and see if that helps. Another thing I noticed is the fuel pump is only pumping about 35psi. I have a manual that says it should be regulated between 41 and 47psi. Could this be the problem? I don't get why the motor runs so great, but won't start. It seems like it's getting enough fuel running. __________________ Milan 1964 Chevelle SS 283/M20

06-22-2003, 12:57 PM	#14
Project1970 14.1 @ 96MPH Join Date: Jul 2001 Location: Mesa, AZ Posts: 2,811	I believe 35 is low...it's definitely a fuel delivery problem of some sort, and that probably isn't helping. I'd also look into the possibility of a clogged injector...I did a bit of research and it looks like LT1's don't have a cold start injector (tuned-ports got rid of them in 1989 or so). Did you run a new feed line from the tank to the engine? I believe the stock line is only appropriate for a return and can't cut it for feed... __________________ Project1970 - LS1 Swap Complete!

06-22-2003, 02:22 PM	#15
70cst10 Senior Member Join Date: Jun 2001 Location: Gaston, SC Posts: 580	Well, we got it running. It turns out, the direction of air flow through the MAF is pretty important. duh... It runs awesome now, and it fires up on the first or second turn (hot or cold). There's still a bit of small stuff that needs to be finished. I'll probably be driving it next weekend. __________________ Milan 1964 Chevelle SS 283/M20



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06-22-2003, 03:06 PM	#16
sgtjed What if? Join Date: Oct 2002 Location: Choctaw,Oklahoma Posts: 649	cool ya got it fixed,the website i posted is down at the moment it seems,but they have some good stuff there. __________________ 2002 red extended cab Silverado 2002 Wheatland yellow Suburban

06-22-2003, 07:38 PM	#17
Blackhawkdc 440 american Horses Join Date: Mar 2001 Location: Anoka, MN USA Posts: 470	check your fuel pressure regulator __________________ Seth Petro 1969 Chev Short Step 425hp 350, TH400, big tires, fast truck 1979 Pontiac Trans Am 1991 Saturn SL1 - gas mileage! (and free) 1977 Buick LeSabre - for sale May America bless God, and may God bless America

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