90 ZR 1 starting

[Bill M.]

Hello my friend has a 1990 ZR 1 with starting problems. The car starts fine when cold. If he drives for an hour or 2 and shuts the car down he has to wait an hour before she will start. When the car is hot it will not even crank. I figure it is the starter but could it be something else ? 20,000 miles original starter. Thanks

[Gary C.]

Re: 90 ZR 1 starting

Bill,

Could be the starter safety solenoid on the clutch pedal. This solenoid is easily by-passed. Remove the driver's side hush panel, it's the big connector at the upper left hand side with 12 gauge purple and yellow wires.

Make a 3 inch long 12 gauge jumper wire with female push on connectors. Unplug the connector and then jump the 2 female terminals with the jumper. I made a spare jumper to carry with me, just in case.

If that's not it, Dave Perry and other ZR-1 members may have other suggestions.

Gary
....

[Mark E.]

Re: 90 ZR 1 starting

Agree with Gary... check the clutch safety switch first; they are not very robust on these cars. Next step would be to check for voltage to the solenoid.

It's worrisome the failure is temperature related since that points to a heat soak issue with the starter or solenoid, which of course are buried in the V of the engine.

[Bill M.]

Re: 90 ZR 1 starting

Mark , Gary thank you I will pass along information

[Mark E.]

Re: 90 ZR 1 starting

Marginal batter cables and /or connections can be affected by temperature too.

[Joe L.]

Re: 90 ZR 1 starting

Hello my friend has a 1990 ZR 1 with starting problems. The car starts fine when cold. If he drives for an hour or 2 and shuts the car down he has to wait an hour before she will start. When the car is hot it will not even crank. I figure it is the starter but could it be something else ? 20,000 miles original starter. Thanks

Bill------


I had this "no hot restart problem" with my 1969 practically from the day it was new. I fought it for years, first under warranty and later on my own. I tried everything I could think of and nothing helped. Then, I asked the best automotive expert I knew, a fellow named Ron Oliphant (one of my few automotive heroes). Without hesitation he told me to install a slave solenoid. I did. NEVER had the problem again. NEVER.

[Bill M.]

Re: 90 ZR 1 starting

Thanks guys we will get into it this weekend . I will let you know outcome. 🔧🔧🔧🛠️ the hammer is for when all else fails

[Donn M.]

Re: 90 ZR 1 starting

Joe.... I've had the same problems with my '70 LT1. Starter, solenoid, battery, TCS, coil, neutral safety switch, ignition switch. etc. have been replaced over the years for several reasons but, hot start problems remain. I use a wire by-pass at the neutral safety switch which works 90% of the time.
What type of "slave solenoid" did you use and how installed to fix the problem ? I checked on line and it appears they are used on power boats ??
Thanks, Donn

[Joe L.]

Re: 90 ZR 1 starting

Joe.... I've had the same problems with my '70 LT1. Starter, solenoid, battery, TCS, coil, neutral safety switch, ignition switch. etc. have been replaced over the years for several reasons but, hot start problems remain. I use a wire by-pass at the neutral safety switch which works 90% of the time.
What type of "slave solenoid" did you use and how installed to fix the problem ? I checked on line and it appears they are used on power boats ??
Thanks, Donn

Donn------

A slave (or, remote) solenoid is simply an old-fashioned starting solenoid sometimes called a "Ford" solenoid. An example of such a solenoid is available under GM #1114532. This solenoid has three lugs----one small and two large. To install the system, first the purple wire to the starter's "S" terminal is removed and transferred to the small lug of the slave solenoid. Next, full battery power is applied to one of the large lugs on the slave solenoid (I took it from the large lug on the existing starter solenoid). Last, the other large lug on the slave solenoid is connected to the "S" terminal on the on-starter solenoid. Larger than stock gauge wire should be used for all of the wiring and connections. I mounted my slave solenoid on the top of the splash shield below the right side fender vents on my 1969.

By the way, my automotive hero Ron Oliphant explained it to me as a problem caused by heat induced high resistance created in the on-starter solenoid's activating wire (S terminal). The slave solenoid ensures that full 12+ volts is applied to the "S" terminal under all starting conditions. The fact that the slave solenoid works so well is pretty good proof that Ron's explanation of the cause is correct.


If I were doing it today, I'd use something like the below-linked kit which includes all the wiring and solenoid.

https://www.amazon.com/Painless-30203-Remote-Starter-Solenoid/dp/B00062Z5QQ

[Donn M.]

Re: 90 ZR 1 starting

Hey Joe, Thanks for the detailed info. on the installation of the slave solenoid. Going to give it a try. You also are an 'automotive hero'.
Thanks for all the continuous information.

Donn

[Domenic T.]

Re: 90 ZR 1 starting

Had that problem on 2 of my cars and one day when I stopped for gas it wouldn't crank. I took the water hose and cooled down the starter and bingo all was well so that worked every time that the starter/solenoid was heat soaked. Drove to my shop and right on the lift and instantly changed the starter which was HOT and it cranked great only to do the same thing when the replaced starter got heat soaked.
Shield will help.

Dom

[Joe R.]

Re: 90 ZR 1 starting

Let us not forget the starter for a ZR-1 is in the valley inside and below the intake manifold. most of the time a starting problem is caused by someone washing the motor and flooding the starter! With the starter placed inside and under the manifold the heat soak becomes a big and real problem.

JR