Jhalsey
Enthusiast
New to this forum and hoping for some help. I have a Gen II Viper engine with a starting problem but its not in a Viper chassis. It’s a Viper crate motor and PCM in a 1972 Datsun 240Z chassis. Long project but its been reliable of late but the other day it stranded me. Parked had breakfast and when I returned it fired right up as usual and then stalled. I could tell right away something was amiss, it never stalls. It fired again and I tried to drive away but again it stalled. Attempted restart, this time it cranked but didn’t even kick. Waited an hour, tried again, no luck so flat bedded home.
At first I thought it was a fuel problem the way it “gradually” died but I have a permanently installed fuel pressure gauge in the engine compartment. With key on I can hear the fuel pump run and the gauge shows 55 psi. I checked the schrader valve in the fuel rail and good spray when depressed. So I’ve dismissed the fuel supply as the problem.
I have the Mopar Viper Crate Motor manual and it explains the start sequence w PCM looking for a crank signal and a cam signal as preconditions to starting. I had replaced the cam position sensor a couple of years ago so I thought I would inspect the crank position sensor which is the original now some 25 years old. Pulled the sensor and w key on, I see 5.2 v on the outside pins and zero on the center connector. I believe the center connector is ground but oddly the center connector shows 48.2 Ohms between it and chassis ground. Not sure what to make of that, perhaps there are some dirty grounds or some harness damage somewhere. I don’t have a scope so no means of testing the sensor. Ordered a new cps, cheaper than a scope.
The wiring on this car is difficult to access, I spent an entire winter on my back head up under the dash and have no wish to repeat that. Pulling the dash is also a bear. With the dash out, I installed two relay centers w fuses on the inside firewall , a total of ten relays w switched and fused outputs. The ASD relay is one of these as is the fuel pump relay. In retrospect, I should have done something more easily accessible. In any case, if the new cps doesn’t cure the problem, looks like I’m destined to pull the dash.
The car has 10k miles on and was built in California. It has a Tremec 6 speed (Tranzilla) and Datsun IRS w Quaife LS. Firewall is moved back 4” and has a full cage. It drives beautifully, when running, torque everywhere. Suspension is coilovers and Wilwood brakes all around w electric brake power assist and electric steering assist.
I will try to attach a couple of photos for your viewing pleasure. If anyone has any ideas for trouble shooting the no start condition, I’m all ears.
Thanks
At first I thought it was a fuel problem the way it “gradually” died but I have a permanently installed fuel pressure gauge in the engine compartment. With key on I can hear the fuel pump run and the gauge shows 55 psi. I checked the schrader valve in the fuel rail and good spray when depressed. So I’ve dismissed the fuel supply as the problem.
I have the Mopar Viper Crate Motor manual and it explains the start sequence w PCM looking for a crank signal and a cam signal as preconditions to starting. I had replaced the cam position sensor a couple of years ago so I thought I would inspect the crank position sensor which is the original now some 25 years old. Pulled the sensor and w key on, I see 5.2 v on the outside pins and zero on the center connector. I believe the center connector is ground but oddly the center connector shows 48.2 Ohms between it and chassis ground. Not sure what to make of that, perhaps there are some dirty grounds or some harness damage somewhere. I don’t have a scope so no means of testing the sensor. Ordered a new cps, cheaper than a scope.
The wiring on this car is difficult to access, I spent an entire winter on my back head up under the dash and have no wish to repeat that. Pulling the dash is also a bear. With the dash out, I installed two relay centers w fuses on the inside firewall , a total of ten relays w switched and fused outputs. The ASD relay is one of these as is the fuel pump relay. In retrospect, I should have done something more easily accessible. In any case, if the new cps doesn’t cure the problem, looks like I’m destined to pull the dash.
The car has 10k miles on and was built in California. It has a Tremec 6 speed (Tranzilla) and Datsun IRS w Quaife LS. Firewall is moved back 4” and has a full cage. It drives beautifully, when running, torque everywhere. Suspension is coilovers and Wilwood brakes all around w electric brake power assist and electric steering assist.
I will try to attach a couple of photos for your viewing pleasure. If anyone has any ideas for trouble shooting the no start condition, I’m all ears.
Thanks
