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Help for trouble shooting for a "no start"

6K views 66 replies 7 participants last post by  JJLT1 
#1 ·
Trying to trouble shoot my no start.
This is a project and thought I was all ready to start it up and all I got was it just cranking over. Heres a little history.

1) LT1 has been rebuilt with the only mods done are .30 over pistons and camshaft

2)I am getting fuel into the injectors, all injectors are getting power(about 12.?? volts) but the plugs are dry..seems like the injectors aren't opening. The last time the engine ran was about 9-10 yrs ago:cry:. I'm sure that there was a small amount of fuel in the injectors but when it came time to put them back in,all I was able to do was shoot some carb cleaner into the top area and where the nozzles were (this was done about a year ago). Hope their not seized up.

3) I am getting spark into the plugs. Therefore I'm pretty sure that the PCM is getting power to run everything else.

4) I am concerned about the oil pressure. Even though I can crank it, I don't get oil coming up into the heads nor does it go up into line from the rear of the intake were I have my mechanical oil pressure gauge hooked up. I have only cranked it over for about 5-10 seconds at a time,about 3-4 times. Was this long enough for the pump to eventually start pumping oil? I was thinking about manually priming the pump by taking off the fittings for the oil pressure and sticking a flat head screwdriver styled rod down it attached to a drill. Is this the right way?

5) As far as it getting air. I guess the MAF is working to regulate the flow.. as long as the PCM is getting power going to it that's all I can assume.

Thanks in advance for the help
 
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#2 ·
Was VATS programmed out of the ECM? That will keep the injectors from firing, even though everything else is working. You may be able to rent a NOID kit at your local auto parts store, to test the injectors actually firing. If they are firing, but no fuel, and you have pressure at the rail, then back to more troubleshooting.
 
#3 ·
Was VATS programmed out of the ECM? That will keep the injectors from firing, even though everything else is working. You may be able to rent a NOID kit at your local auto parts store, to test the injectors actually firing. If they are firing, but no fuel, and you have pressure at the rail, then back to more troubleshooting.
Yes, when I initially swapped the LT1 in about 10 yrs ago I drove it in the elky for about 2 weeks before I started my project and the PCM was reflashed.
 
#4 ·
injectors may be stuck??
they get 12v all the time, the ecm triggers the ground..

is the oil filter full of oil??
you may not have cranked it long enuff ether
sometimes it takes about 30-40sec in a row of cranking for my hotrod to show pressure..

no you cant prime the oil pump on a lt1 without removing the intake and pump drive stub/gear..

:texas:
 
#6 ·
injectors may be stuck??
they get 12v all the time, the ecm triggers the ground..

is the oil filter full of oil??
you may not have cranked it long enuff ether
sometimes it takes about 30-40sec in a row of cranking for my hotrod to show pressure..

no you cant prime the oil pump on a lt1 without removing the intake and pump drive stub/gear..

:texas:
injectors may be stuck??....it would seem strange that their all stuck, but not under the circumstance that its been sitting all these years....is just lightly tapping the sides the remedy to free them up?


they get 12v all the time, the ecm triggers the ground.....how would I know if the ECM does trigger the ground..is there something I can checked?

is the oil filter full of oil??.....MMMM idk...I would think maybe not, considering I cant get oil up into the heads...but that reminds me of when the first time I tried to crank it over (10 yrs ago) and it wouldn't start...couldn't figure it out and then I connected the 2 brown wires going into the side of the oil pan for the ...I believe its the "low oil level sending unit"...those 2 wires were jus dangling there so I connected them and she started right up...took me a week to figure that one out...
this was the first time I started to realized that "going from old school carburetor to new school fuel injection was what put the fear into some people.

you may not have cranked it long enuff ether....ok , I didn't want to crank it too much considering that all I have in the cylinders and heads is engine lube.


no you cant prime the oil pump on a lt1 without removing the intake and pump drive stub/gear.....ahhhh...ok, I was trying to make sure that the oil pump was turning so when I pulled the valve cover I saw my rockers going up and down so I assume since the pump is meshing with the cam that its working too, that was the only thing I could think of to do.
 
#5 ·
OK, so VATS should not be the issue. I would then get the NOID lights and see if the injectors are firing. You can also measure the resistance of the injectors to be sure they are not open ( 14-16 ohms nominally) ( wouldn't expect all of them to be open, nor would I expect all of them to be plugged up either). Injectors fire via a ground signal from the ECM. Would have 12V all the time- just waiting for the ground signal to fire. If you have 2 fuses for injectors, make sure both are good.

How's your fuel pressure? Assume pump primes for 2 seconds, then cuts off. regulator holding pressure for at least a couple of minutes after pump shuts off? Pump should re-start when Oil Pressure builds, or revs show engine is running. A lot depends on how the relay was wired- could have been wired direct with no Oil Pressure switch. Will engine run using starter fluid squirted in the TB?

Engine should start whether MAF is plugged in or not. If not plugged in or defective, ECM will use a default table. IAC is involved more with starting, but again should not inhibit it totally.

Not sure how to prime an LT1- hopefully JJ jumps in:biggrin:
 
#8 ·
OK, so VATS should not be the issue. I would then get the NOID lights and see if the injectors are firing. You can also measure the resistance of the injectors to be sure they are not open ( 14-16 ohms nominally) ( wouldn't expect all of them to be open, nor would I expect all of them to be plugged up either). Injectors fire via a ground signal from the ECM. Would have 12V all the time- just waiting for the ground signal to fire. If you have 2 fuses for injectors, make sure both are good.

How's your fuel pressure? Assume pump primes for 2 seconds, then cuts off. regulator holding pressure for at least a couple of minutes after pump shuts off? Pump should re-start when Oil Pressure builds, or revs show engine is running. A lot depends on how the relay was wired- could have been wired direct with no Oil Pressure switch. Will engine run using starter fluid squirted in the TB?

Engine should start whether MAF is plugged in or not. If not plugged in or defective, ECM will use a default table. IAC is involved more with starting, but again should not inhibit it totally.

Not sure how to prime an LT1- hopefully JJ jumps in:biggrin:
Darbysan...I was replying to JJ before i saw your post....

I would then get the NOID lights and see if the injectors are firing. You can also measure the resistance of the injectors to be sure they are not open ( 14-16 ohms nominally) ( wouldn't expect all of them to be open, nor would I expect all of them to be plugged up either). Injectors fire via a ground signal from the ECM. Would have 12V all the time- just waiting for the ground signal to fire. If you have 2 fuses for injectors, make sure both are good.......oh,..ok..I was looking in my service manual about the testing of the injectors but wasn't quite sure what that tester was that it was showing nor to savy on how to interpret it i guess its what your referring to as the "NOID lights ".. I"ll try that OHMs test and double check the fuses like you said.


How's your fuel pressure? .......pump is pumping but my pressure gauge on the Schrader valve doesn't read any PSI...suppose to be 43.5 psi ,, right?
Assume pump primes for 2 seconds, then cuts off......actually,before I had an MSD fuel pump hooked up with a 30amp relay then to the 15 amp fuse..it worked. Now I went back to the OEM pump in the tank, I noticed that after the key was on,and it pumped fuel, the fuel did shut off... I didn't understand why so I went back to hooking my in tank pump straight to a 30 amp relay then to the 15 amp fuse...it runs constantly now. This is a brand new Delphi, that puts out 65-90 psi.

regulator holding pressure for at least a couple of minutes after pump shuts off?........mmm not sure but this is also a brand new Delphi regulator


Pump should re-start when Oil Pressure builds, or revs show engine is running. A lot depends on how the relay was wired- could have been wired direct with no Oil Pressure switch.......... I wired it 2 ways...1 way with the oil pressure switch hooked up and now with it direct (w/ the mechanical oil gage)

Will engine run using starter fluid squirted in the TB?....didn't try that considering I stopped when I saw I had no fuel going into the cylinders.

Engine should start whether MAF is plugged in or not. If not plugged in or defective, ECM will use a default table. IAC is involved more with starting, but again should not inhibit it totally. .........ok, thanks
 
#7 ·
You say you're getting fuel to the injectors, but is the pump on and making pressure? You mention oil pressure, so that's why I'm asking. LT1's have a 'failsafe' in factory installs such that no oil pressure at the sensor means no fuel pump run. Bad sensor or no oil pressure prevents it. Just a thought.
Patrick
 
#12 ·
hi Patrick,
yes, I am getting fuel to the injectors...not sure about that pressure...cant see any PSI on my pressure gage I have hooked up to the Schrader valve.

I took off the OEM pressure sensor...(are we talking about the one at the rear of the intake?) and installed a mechanical gage...its been some time since I did the original swap out from the caprice but I recall it maybe only had a warning light...that's why I went with a mechanical,c ause I wanted to see the oil pressure...if I recall the 3 wires coming out of the pressure switch...they were, Orange for 12v, gray was tied into the fuel pump orange for 12v in case the fuel pump lost 12v juice and the tan was for the gage/idiot light...but like I said..i think it was the idiot light.

could it be that it does have to have an oil pressure switch hooked up? cause I went on autozone..just looking at the oil pressure sensors and it listed 2....1 sensor if equipped with warning light and 1 sensor if equipped with gauge.....if so than that means I can not go with a mechanical gage..i would have to go with an electric one??
 
#9 ·
x2 on the NOID light to see if the ecm is trying to fire the injectors..

x2 on the startin fluid, running it some may free up some stuck injectors,
yes they do stick, they can stick open/leak too..
now days fuel gets real funky in 9-10yrs.. some fresh gas in there may help??

if you changed the filter? if you did not fill the filter with oil? it will take a lot of cranking to fill it..
you can backfill the oil gallys from the oil pressure port..

:texas:
 
#14 ·
With the Fuel Pump running, you should be seeing 40-50 PSI of pressure at the fuel rail. If not, need to check from there back to the tank- May be a plugged filter, or split connection hose in the tank. The hose in the tank that connects the pump to the sender needs to be a "special" grade of fuel hose (SAE 30R10), designed for being submerged in gas. Normal Fuel Injection hose will disintegrate over time when submerged. I've even seen the special stuff be bad out of the box, especially when it is supplied as part of a kit. Maybe just shelf life on the kit stuff.
 
#16 ·
Starting fluid is the modern equivalent of pouring a splash of gas into the carb. It's a great diagnostic tool. The fuel pump/oil pressure correlation is something I have knowledge of as a parts man and article reader (who works on his old carbureted stuff but merely maintains and repairs the FI stuff that gets us around), not as a Chevy FI tech, so it's just a thought.
Patrick
 
#17 ·
x2 the starting fluid is just easyer on a front mounted throttle body,
you can shoot it thru a vacuum hose too into the manifold real easy..

the EFI fuel pump power is a common error, it has 2 sources for power normally,,
the car will still start even if the relay goes out
but, waiting for the oil pressure switch to close will cause a long cranking times..
:texas:
 

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#18 ·
hi all.....last night when I got home I did some more trouble shooting.

1) getting oil pressure now...first thing I did when I got home was spin off the filter.. when I cracked it loose it was full and running out...it must have filling up all that time..started cranking the engine and noticed oil coming up the oil pressure gage tubing..the heads are just beginning to be wet. I also screwed the OEM oil pressure sensor back on and connected the Orange(+), the gray to the FP orange wire and the Tan wire to the gage or warning light is still not connected and tried it that way too.......so it looks like I'm good on the oil pressure side...

2) Seems like I got plenty of fuel pressure..even though not sure at what PSI. when I loosen up the fitting on the Schrader valve..fuel sprays out...not sure why that New Summit Racing brand fuel pressure gage isn't reading. I noticed a very small, looks like adjusting screw way up inside..but I don't think it needs adjusting:dontknow:. The OEM Delphi fuel regulator is non adjustable . fuel tank is new, new pump with the SAE30r10 hose (about 3 in. long), new fuel hose,new fuel filter. I do have the charcoal filter canister hooked up with the 2PSI check valve..i found space and mounted the canister at the pass. side rear area on the frame, right in front of the bumper "shock"..the lines are all clear.



3) Got some starting fluid and sprayed it into the TB and tried starting it...Man,that baby wants to start..but nothing..it fires up for a few seconds until the starting fluid evaps then just cranks over.:-(

4) Plugs are still dry...they are just a little damp with engine lube

5) did I forget anybody's question.....Oh, I may take that fuel pressure gage off and put it on my truck to make sure it actually works
 
#19 ·
Since it's trying to start with the starter fluid, that confirms that you are getting spark and air. Only thing left is the fuel.

On the fuel gauge, sounds like it is a permanently mounted gauge. Does it have the provision inside it to depress the Schroeder valve when installed, or does it require that the valve be removed?

I think you need to confirm what pressure you are seeing at the rail to determine if the injectors are clogged. Noid light will also confirm that you are getting a proper signal from the ECM to fire the injectors. I would confirm both of those before going through the steps to remove and clean/replace the injectors.
 
#20 ·
Since it's trying to start with the starter fluid, that confirms that you are getting spark and air. Only thing left is the fuel.

On the fuel gauge, sounds like it is a permanently mounted gauge. Does it have the provision inside it to depress the Schroeder valve when installed, or does it require that the valve be removed?

I think you need to confirm what pressure you are seeing at the rail to determine if the injectors are clogged. Noid light will also confirm that you are getting a proper signal from the ECM to fire the injectors. I would confirm both of those before going through the steps to remove and clean/replace the injectors.
I have to remove the valve, then install the pressure gage. i'll put the gage on my truck and see if theres a reading..just to check the gage.
 
#22 ·
if fuel comes out when you loosen/unscrew the gauge, then the shrader valve is open.. :texas:
yes, I remove the valve stem then install the gauge and yes when I loosen the fitting from the gauge that's on the shrader valve, fuel sprays out. I didn't have time to mess with it to much last night but I have no "shrader accessible valve " to install the pressure gauge on my truck..I'm getting a hold of summit for a replacement..and try to see if its the gauge
 
#23 ·
Local Auto Parts stores here rent (free) the Fuel Pressure gauge. Don't know if you have that in feature in Hawaii.
 
#24 ·
Local Auto Parts stores here rent (free) the Fuel Pressure gauge. Don't know if you have that in feature in Hawaii.
oh, I didn't think about that, I'll check autozone(they just came here last year)oreillys, napa and carquest and see if that's one of free rentals. But, I just called summit about the gauge, I told him the first time I used it was about 4 days ago and it didn't work. when he checked my order# I ordered it aug of 2015..he said laughing..its a little out of warranty but i'll send you a new one...no need to send the old one back..he said it would be about 3 days:nanawrench:. I've had to get a replacement on parts twice before and have had 0 problems with them. Very courteous, apologetic and they make sure I get the replacement ASAP. So, we'll see how this new gauge works, hopefully its a good one and the other one WAS bad.
 
#26 ·
that's sad...if it failed right out of the box,...I rolled my eyes when I got it...saw dat shiney oval gold lable that said "made in Taiwan"...but I guess its a step up from the other gold label that says made in PRC. i'll check it with air when I get home
 
#27 ·
They have it in stock if this store is close to you.

http://www.autozone.com/loan-a-tools/fuel-pump-diagnostic-kit


AutoZone
4561 SALT LAKE BLVD
HONOLULU, HI 96818
(808) 485-0592



OEM Fuel pump diagnostic kit



Price: $157.99

Part Number: 27167
Warranty: 3 months
Notes:









Store Pick Up

In Stock




Ship To Home

In Stock
 
#31 ·
well, after last night...It looks like I may not be getting enough fuel pressure. I went and rented the Diagnostic fuel pump kit @ A.Z. Hooked up the gauge and.... no PSI...not even on the first increment of 2 psi...so I checked my summit gauge with air pressure (from JJ)...and it reads...so then I checked the A.Z. gauge....it also reads. I went and hooked it up before the fuel filter and still nothing..it does have a small amount of pressure when I do put my thumb over the hose end but obviously not enough read 2psi. From the filter back to the top of the tank looks good..no restrictions. So I'll pump out what fuel I can out of tank (about 5 gals), drop the tank,pull out the pump and test pressure with just the pump.:(
 
#32 ·
Good work. The pump usually has a couple of culprits. 1) Split / disconnected hose. 2) Pump wired backwards ( pos and neg reversed). 3) just a bad pump. 4) some applications had a Pulse Inhibitor between the pump and the sending unit. If yours has that, get rid of it and just use hose. On the newer pumps, it's not needed. They tend to be a leaking point when old.

If you have to replace the pump, I've found the AC Delco EP381 to be very good, and also very quiet. Much quieter than the Walbro 255 I have in mine now.
 
#33 ·
AAAAHHHH....I think I found the problem....:

I think when searching for the pump I wanted to make sure it fit in the 1986 4.3 FI elky's sending unit and enough PSI, but I made sure I told the parts guys it was for a 94 caprice w/5.7 LT1

Napa guy a while back says "hey use the Delphi FE 0110 its from an 89 IROC Z and it also fits the caprice"...so this is what I have now.

The Delphi FE 0110 is for the 4.3 V8 in the caprice...10.5 amp/16gph

What I need is the Delphi FE 0114, its for the 5.7L in the caprice ......13 amp/27gph

I double checked this on rock auto (they list both), AutoZone, Napa online, this is probably the reason why I don't have enough pressure
 
#36 · (Edited)
check that before dropping the tank..

what ever pump it is, it should make some pressure..

:texas:
I'll double check that again...when I turn the key on, I do hear a faint humming noise coming from the tank...so, on the pump +/-...if it does happen to have the wires reversed it will still run? still pump? but probably not as suppose to be?
 
#35 ·
The Fe110 should be a 50 PSI pump, while the FE114 should be about 60 PSI, according to the date at Rock Auto. Either one should be able to produce pressure at the fuel rail. The smaller one might run out of fuel at WOT or High RPM's, but it still should be able to run the vehicle at idle +.

Something is preventing fuel pressure from building- either wiring or internal connection of the pump to the sender.
 
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