Ignition cuts out after running for awhile

[drz712]

I have been running fuel on my motor for several years now and decided to add ignition control. I am using a GM 8 pin HEI module on a small block chevy. I installed the distributor wired it up set up the base timing, connected the 5v reference and set the trigger. The motor runs great and advances just like in my spark table i set up. The problem is once the motor runs for quite awhile even way after the warmup enrichment is off it cuts out. When I try to restart the motor it fires and dies right away. If i let the motor cool down it will fire right back up and advance will work fine again until it gets hot again. My settings are input capture of rising edge, cranking trigger is trigger rise, coil charging scheme standard, spark output going high. Has anyone else had similar problems or have an idea

[Bernard Fife]

drz712,

Sounds like either the module or the coil might be overheating. In any case, you will probably want to post an MSQ and datalog to get more help here.

Lance.

[drz712]

After i posted I checked all my wiring just to be sure and ran the motor again. Again it cut out as it got hot.. I quickly changed the 8 pin module and it fired right up where before it would not fire. I ran the motor for 20 minutes idling and it did not die and then I drove around for several miles and it seems to be fixed. The module that kept cutting out was a brand new module. Is it possible I got a bad module in a brand new distributor. It is a Mallory with Hall effect sensor. I do have these two datalogs. One is when the motor died when hot, there is a few revs in the log too, at the end is where it died and then I tried to restart it several times. Then the other one is with the new module. If anyone could tell me if it looks good I would appreciate it. Thanks

[Bernard Fife]

drx712,

It is certainly possible to get a bad brand new module. The quality on these seem to be all over the map. When I get a new one, I put it in and try it for a few days before deciding if it is 'good'. But I keep a 'known good' one (that has proven to run well for at least week or so) on hand as a backup at all times. The bad ones get tossed so they don't get mixed up with the good ones. My experience is that if one runs well for a few days, it will be good for many thousands of miles.

Lance.

[impalakid68]

I have the same problem, 71 Chevelle small block 383, 29lb. injectors running MS2 ver3 with 2.89. Engine runs fine for about 25 minutes water temp. reaches 175 - 180 degrees AFR set at 14.0 then starts swing between 12.0 to over 16.0 then dies. Let it sit between 15-30 seconds it will restart. I am running a used GM HEI8 small cap. I replaced the pick-up coil (did help smooth out idle), then purchased 2 new modules (same brand) - would not start with either one. Went to a different parts store purchased another module - engine started. But, I still had the same results as the stock GM module. The magnet had two cracks, I checked using a screw driver, magnetism seemed good for the 8 positions.

I also had a issue blowing the fuse for the fuel pump. This is a new tank with a internal pump. This a intermittent problem. I checked the amp draw, it is about 8 amps, so I went from a 10 amp fuse to 15 amps. Figuring +or- tolerance in the fuse and spikes in amps. After the engine died I disconnected the pump wire from the MS relay board and went straight to the battery. Ran the pump for over an hour with out a problem - without the engine running. Thinking I had a pump problem.

I have replaced and swapped 2 relays (pump and injectors) on the MS relay board and three that are in my wiring harness. Problem not solved.

[Matt Cramer]

Could you post an MSQ and a data log of the engine dying?

[impalakid68]

Well I hope this will help. I will say that this time the engine went lean, died and then the fuse blew (15 amp) for the fuel pump. I did not check the fuel pressure this time, when it died. Usually it stayed at 30 psi., even after it leaned and died. The fuel pressure is 30 psi. at idle, and will go to 85 psi. when I pinch off the return line. I also have a new MSD coil, that has been on the engine since before the dieing issue.

I guess I am leaning toward a fuel pump problem. To me it seems to have a spot were it seems to have a issue. Please check the msq for any issues with my settings.

Thank You for the help, Adrian

[Matt Cramer]

It looks like you don't have a good RPM signal. When the RPM signal drops out, the ECU will turn the fuel pump off until it comes back again.

[impalakid68]

Hello again

I used MSnS-E modification (option 2) with the 1k res. first. Then switched back to the 390 resistor. I checked both R52 and R56 and they are ccw to the click. With the 1k res. the engine just died. With the 390 res. the fuel pump fuse blew.

[trakkies]

The pump fuse blowing should be a red herring - as it should be in the pump power circuit, so nothing to do with MS. MS should only control the relay coil.