LT1-LT4 Modifications 1993-97 Gen II Small Block V8

LT1 getting worse on starting

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Old 07-20-2012, 01:21 AM
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Default LT1 getting worse on starting

So I have been having an issue with starting recently. Crank and no start but after 2 or 3 tries it would fire up fine. Today after driving to work about 30 miles it ran perfect but when I parked it started getting a little rough on idle. I shut it off for a second and re-started and normally after running it would fire right up but not this time. Took 3 tries and when it finally did start it was really rough as if it were missing and then the rpm raced up to about 2200 for a second and then dropped back to around 900 (normal).

I had no choice but to go into work and hope I could at least get home. After work it did its normal 3 tries before starting but was rough for about 10 seconds and then evened out. When I first started out it hiccuped once and then ran fine the whole way home.

Does this sound like a fuel pressure regulator or an ignition problem?

Any advice would be appreciated. Im going to try and borrow a fuel pressure gauge but I dont have alot of experience with the LT1

Thanks
Old 07-20-2012, 09:42 AM
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You can pull the vacuum line on the FPR and check if fuel drips out or if there's a fuel smell. Mine has a fuel smell and gives me some problems starting up.
Old 07-20-2012, 09:46 AM
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SES light? Maf and o2 issues can cause same symptoms
Old 07-20-2012, 10:38 AM
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No lights yet.....
I know it works because I unplugged the Maf a few days ago to see if I still had issues with it unplugged and the SES light came on and stayed on for a few miles after I plugged it back in.

Im baffled. I would hate to just start blowing $$$ replacing sh*t that isnt broken.

Unrelated Im pretty sure my AC compressor is going as it started making noise and Im hoping thats all that is because there is this crackling noise that I cant seen to pinpoint when the ac is off. It gets worse when the AC is on but like I said I cant seem to figure out exactly where its coming from other then the front of the engine and more audible on the passenger side. It almost sounds like a piece of plastic rattling around inside something.

any thoughts??
Old 07-20-2012, 11:15 AM
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Start with testing the fuel pressure and regulator. The hard start sound like a fuel pump going out. Mine would do this when I bought it. Put in a new pump and never had a problem since.
Also, when was the last time a tune up was done and how many miles are on the car?
Old 07-20-2012, 12:08 PM
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I blame the temp sensor in the water pump, but then again I always do when there are problems like this. It's one of the easiest and cheaper parts to replace. If it's bad it can cause a whole mess of problems. When mine was bad I was running really rich, care would only start if I held the gas to the floor, misfires at high rpms, shuttering at stop lights etc. the list went on and on. $20 and 5 minutes later my problems were solved.
Old 07-20-2012, 12:58 PM
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Im still trying to borrow a pressure gauge. Only place near me is a NAPA and they are double price on everything.
I have no idea when a tune-up was done or ever done. I just picked it up about 2 months ago and the previous owner had great records of maintenance but nothing indicating plugs wires etc.... Vehicle now has 109000 and ive put 2000 on it. All ive done mechanically is changed the oil, filter, air filter and cleaned the MAF with the correct spray. The first thing I checked was the MAF.

You mentioned temp sensor? Im not having cooling or temp gauge issues at all. And the hard start happens hot or cold. Just now I moved the car closer to my house and it took 4 times to finally get it running. I can hear the pump each time I turn the key and its not loud and I barely hear it with all the dings and such when the key is turned lol.

I need to wait for early evening as I dont have a garage and its screaming hot outside.

thanks again for the advice all

Still havent gotten a gauge but I changed the fuel filter and I wasnt so lucky with that being the issue. Will keep trying
Old 07-22-2012, 10:09 AM
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When it won't crank floor it while turning it over, as soon as it busts off let go of the throttle.. From time to time I must do this (mostly if its hot and recently been shut down)..
Old 07-23-2012, 09:25 AM
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Yea that didnt do me any good. Tried flooring it but same results. It looks like im just gonna have to go out and buy some fuel pressure gauges. Im tired of waiting on others. Sux that I have to blow $45 to use it once. Next step I guess is fuel pump?
Old 07-23-2012, 09:35 AM
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Originally Posted by betterbait
Yea that didnt do me any good. Tried flooring it but same results. It looks like im just gonna have to go out and buy some fuel pressure gauges. Im tired of waiting on others. Sux that I have to blow $45 to use it once. Next step I guess is fuel pump?
Mount one permanently on the rail , I did .. It's good to be able to check a fuel pressure issue by just popping the hood..
http://item.mobileweb.ebay.com/viewi...d=260323647895
Old 07-23-2012, 11:42 AM
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I was actually thinking of adding a gauge cluster inside and fuel pressure will definitely be a handy gauge
Old 07-23-2012, 11:54 AM
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If you want to delete your HVAC, you can mount the 2" and 2-1/16" gauges inside of your vents. They fit in them perfectly. Then you can mount a custom switch panel where the HVAC was for stuff like a manual fan switch, nitrous, all sorts of goodies.
Old 07-24-2012, 09:58 AM
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Sounds good but this is my daily driver and I need AC. Hot all year round here in the Florida Keys .....

I picked up a pressure gauge yesterday and will be testing it today. On the topic of Fuel pump, which would be the best replacement and do I need the entire assembly like this one: http://www.ebay.com/itm/ACDELCO-OE-S...fa655b&vxp=mtr

or just a pump like this:
http://www.ebay.com/itm/NEW-PIERCE-P...436abc&vxp=mtr


What brands are good and what to stay away from? Another member told me racetronix is what he would use?

Thanks

Ok so the results are in
I wanted to make sure the car had not been running for a while so I let it sit overnight before testing.
Hooked up the gauge and it was 0 so no pressure at all after sitting. I turned the key and it barely moved. I released the key and turned again and it went up a little but dropped as soon as I reset the key. If I turn and release the key about 6 times it would reach 20psi and start. Once started it maintained 36-38 with no fluctuations. As soon as I turned it off the pressure dropped immediately ( about 10 seconds) back to 0.

So its not giving enough on 1 key turn to start the vehicle and as soon as I release the key it drops. I checked the FPR and its clean (no fuel) in the vac line and not even wet so Im guessing its a pump going or ???

Either way its staying parked because my ac compressor is making some crackling noise even when not turned on so the last thing I need is for it to seize up and throw a belt or worse leaving me stranded somewhere other than home.

Fuel tank is almost empty so dropping it will be a little easier. Any tips on that? I really dont want to cut a panel in my floor but will if all else fails.
Old 07-24-2012, 12:52 PM
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I think it's safe to say the pump is toast. If it is immediately bleeding off pressure like that, it's time to replace it. I would upgrade while your in there or if its not a big deal to you just go factory ac delco.
Old 07-24-2012, 02:43 PM
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Id personally go with the racetronix kit also. Its cheaper in most cases than a stock replacement and it will be there when your ready to mod. I'd also just go ahead and cut the trap door, makes things much easier.

As far as the noise your hearing are you sure its not the tensioner pulley? That'd be my first suspect.
Old 07-24-2012, 04:04 PM
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I ran the Racetronix kit. I haven't done the hotwire, but the fuel pump kit was well worth it. It's slightly intimidating, but it's not nearly as bad as it seems. I just made sure to let the assembly sit overnight for the glue to cure. I know my luck with glue.

I cut the trap door also. I cut it a little bigger than most of the diagrams show because I fought the damn fittings on the fuel pump. Said to hell with it and cut it a bit bigger.
Old 07-24-2012, 09:21 PM
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Sounds like the check valve inside the fuel pump, when it goes bad it doesnt hold pressure and you get extended crank. Thats why your seeing fuel pressure drop after it primes up.

While car is running the pump works fine but the check valve in the pump bleeds off the pressure if its not working correctly. Either way probly time for new pump. Racetronix makes good kit, i would look into getting there wiring harness aswell.
Old 07-25-2012, 09:47 AM
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I looked at the racetronix and its is a walbro pump. My nephew got 2 bad walbros when he did his camaro last year. Any other descent pumps? Advance auto only has the whole assembly for an exact fit. Is airtex any good? I want to try and keep it local so in case I have a problem then Im not stuck for a week trying to get a replacement.

thanks again

Just an update.
Replaced fuel pump and that fixed my issue with starting. Great fuel pressure and ignites on single turn of the key

awsome thanks all!!!

Now Im working on the AC compressor. I got the old 1 out and decided to take a day off lol. What a PIA to remove it.

Originally Posted by Fazz73jr
Id personally go with the racetronix kit also. Its cheaper in most cases than a stock replacement and it will be there when your ready to mod. I'd also just go ahead and cut the trap door, makes things much easier.

As far as the noise your hearing are you sure its not the tensioner pulley? That'd be my first suspect.
The compressor was bad but the other noise I mentioned WAS the tensioner pulley. Replaced it while doing the ac and noise is gone

thanks man



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