Uk member C4 non start
Thread Starter
Heel & Toe
Joined: Aug 2022
Posts: 23
Likes: 0
Uk member C4 non start
Hi Guys,
a big thanks in advance to all that may be able to help me here.
Here is where I find myself after 6 weeks of pain trying to start my 1990 L98 engine which is fitted into my 1951 3100 truck.
New fuel pump, filter and pipes from tank to fuel rails, 41psi at gauge on rail.
Vats bypass installed at 30hz.
New coil, rotor, ignition module, cap and spark plugs.
I have used the original 1951 ignition switch and installed a starter button on the dash.
Fuel pump primes, 40psi obtained at rail.
Engine cranks but doesn’t catch unless I spray starter fluid into the plenham, however last weekend it did run twice in a row but after turning the ignition off would not re start.
Sprayed starter fluid into the plenham and it started and ran until turned off then nothing again!
I have spark at the plugs, good oil pressure, the taco needle moves when I crank the engine but no pulse at the injectors.
There is 12 v coming into the injectors from the fuse block side.
Ohm readings as follows
No1 = 15ohms
No2-8 = 13ohms
Would sticky injectors cause this no pulse scenario with it running great when it does start or is there a problem I’m just not seeing?
p.s. I’m a novice at injection and all I’ve learnt is from you guys on here, so thank you for your input and sharing of knowledge.
a big thanks in advance to all that may be able to help me here.
Here is where I find myself after 6 weeks of pain trying to start my 1990 L98 engine which is fitted into my 1951 3100 truck.
New fuel pump, filter and pipes from tank to fuel rails, 41psi at gauge on rail.
Vats bypass installed at 30hz.
New coil, rotor, ignition module, cap and spark plugs.
I have used the original 1951 ignition switch and installed a starter button on the dash.
Fuel pump primes, 40psi obtained at rail.
Engine cranks but doesn’t catch unless I spray starter fluid into the plenham, however last weekend it did run twice in a row but after turning the ignition off would not re start.
Sprayed starter fluid into the plenham and it started and ran until turned off then nothing again!
I have spark at the plugs, good oil pressure, the taco needle moves when I crank the engine but no pulse at the injectors.
There is 12 v coming into the injectors from the fuse block side.
Ohm readings as follows
No1 = 15ohms
No2-8 = 13ohms
Would sticky injectors cause this no pulse scenario with it running great when it does start or is there a problem I’m just not seeing?
p.s. I’m a novice at injection and all I’ve learnt is from you guys on here, so thank you for your input and sharing of knowledge.
Le Mans Master
Joined: Feb 2005
Posts: 6,481
Likes: 566
From: Clearwater Florida
..... Try tapping on the injectors with a wooden or hard plastic dowel or such while an assistant cranks it ... injector plungers can stick if they had fuel in them then sat for a while ... have you been able to check the timing at all ? ... a No-pulse at the injectors can also be caused by a defective ignition module in the distributor or connectivity issues for the same to the ECM ... the computer has to see the signals that confirm that the engine is being started/cranked ... another possibility would be that the ECM sees the TPS above 50-60% ... that puts the fuel delivery into "clear flood" mode ... another wiring/connectivity thing .....
Last edited by C409; Sep 18, 2022 at 11:10 AM.
Thread Starter
Heel & Toe
Joined: Aug 2022
Posts: 23
Likes: 0
Start issues
Hi guys thanks for getting back to me.
I had the engine running those three times I mentioned with the vats bypass set as it is now.
I then considered it could be the ignition module having an intermittent fault so replaced that, checked continuity of the wires from the distributor to the connector, all good.
I do need to check from the connector to the ecm though!
I’ve tried tapping injectors while cranking but nothing.
I just don’t understand if vats wasn’t being bypassed properly then how come it ran three times and now nothing.
It is stock ecm, ccm etc
I tried the a to b on diagnostics and bizarrely the radiator cooling fans and fuel pump came on ???
I had the engine running those three times I mentioned with the vats bypass set as it is now.
I then considered it could be the ignition module having an intermittent fault so replaced that, checked continuity of the wires from the distributor to the connector, all good.
I do need to check from the connector to the ecm though!
I’ve tried tapping injectors while cranking but nothing.
I just don’t understand if vats wasn’t being bypassed properly then how come it ran three times and now nothing.
It is stock ecm, ccm etc
I tried the a to b on diagnostics and bizarrely the radiator cooling fans and fuel pump came on ???
Pro
Joined: Aug 2020
Posts: 647
Likes: 126
From: Liliha Bakery stuffing my face with coco puffs!
Radiator cooling fans coming on with A-B shorted is normal. I'm more intrigued with the CCM...I know in your other thread you asked if you need to still keep it with the signal generator??? Reason I mentioned, I wish I bought a older vette so I wouldn't have to contend with the CCM. PO dealt with a no start issue and had the CCM sent out. I cringe at the fact that the CCM could leave me stranded. Anyhoo...I wouldn't think you need it unless you're fuel system and starter enable relays have been part of your retrofit. Hate to throw darts at this thing but old worn out pick up coils have been known to cause intermittent no starts. 
Thread Starter
Heel & Toe
Joined: Aug 2022
Posts: 23
Likes: 0
Hi Stew and thanks for your reply.
I have used the ccm as I have engineered the pump and sender unit from the corvette tank into the 3100 tank also having engineered the whole suspension, brakes etc under the truck I also wanted to keep abs if I could?
The pick up coil I haven’t changed, any way of testing?
Also where would I see the faults code, instrument cluster or dics, instrument cluster is plugged in but not all wires are connected as I will have new period gauges at some point and only want the basics which are working on the instrument cluster.
I have used the ccm as I have engineered the pump and sender unit from the corvette tank into the 3100 tank also having engineered the whole suspension, brakes etc under the truck I also wanted to keep abs if I could?
The pick up coil I haven’t changed, any way of testing?
Also where would I see the faults code, instrument cluster or dics, instrument cluster is plugged in but not all wires are connected as I will have new period gauges at some point and only want the basics which are working on the instrument cluster.
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Thread Starter
Heel & Toe
Joined: Aug 2022
Posts: 23
Likes: 0
Hi guys,
latest update is that she’s now running, I found an intermittent wire break on the purple and white from the ignition module to the ecm. However still no start!
Then even though it had started three times on the 30hz bypass I thought I’d just try the 50hz and bingo off she went.
Go figure that one out🤔.
once again thanks for your input guys
latest update is that she’s now running, I found an intermittent wire break on the purple and white from the ignition module to the ecm. However still no start!
Then even though it had started three times on the 30hz bypass I thought I’d just try the 50hz and bingo off she went.
Go figure that one out🤔.
once again thanks for your input guys