[stich]

I got the car started and runs really strong upon start up but after it warms up, it refuses to restart. I've got the sniper system with an MSD dist. and Blaster coil all on a bit pumped up 455. It gives a tiny "wanna" start while first cranking but then nothing. I can hear the fuel pump run for 5 seconds when I turn on the key and the gauge reads 60 lbs of pressure at the intake of the Sniper. I've tried advancing the dist 10 degrees both ways while cranking. Still nothing. After a couple hours, she starts up fine again. I'm baffled and have to admit, I know absolutely nothing about the electronical readings on the Sniper computer screen. I'm about ready to take it to a tune shop but there isn't one close enough to me to drive to. I've got around 150 miles on it so far. Suggestions?

[Scott65]

Likely has to do with either the priming pulse, and or cranking pulse under hot conditions. Should take much less fuel to start hot than cold. I don't know the Holley that well, so hopefully someone else will chime in with correct terminology for Holley. But reducing the (priming/cranking) fuel in hot start conditions is likely where you need to be looking.

[Gary H]

Originally Posted by stich

I got the car started and runs really strong upon start up but after it warms up, it refuses to restart. I've got the sniper system with an MSD dist. and Blaster coil all on a bit pumped up 455. It gives a tiny "wanna" start while first cranking but then nothing. I can hear the fuel pump run for 5 seconds when I turn on the key and the gauge reads 60 lbs of pressure at the intake of the Sniper. I've tried advancing the dist 10 degrees both ways while cranking. Still nothing. After a couple hours, she starts up fine again. I'm baffled and have to admit, I know absolutely nothing about the electronical readings on the Sniper computer screen. I'm about ready to take it to a tune shop but there isn't one close enough to me to drive to. I've got around 150 miles on it so far. Suggestions?

Where are you getting your power for the sniper, and coil from? Also, do you have electric fans that would be running when it's hot and trying to restart the engine?

[ID67goat]

When this happens, are you trying to start it without touching the pedal? Does it smell rich like you are flooding the engine?

[stich]

Originally Posted by Gary H

Where are you getting your power for the sniper, and coil from? Also, do you have electric fans that would be running when it's hot and trying to restart the engine?

Power for Sniper is directly from battery, coil direct from ignition. No electric fans.

[stich]

Originally Posted by ID67goat

When this happens, are you trying to start it without touching the pedal? Does it smell rich like you are flooding the engine?

I've tried both ways, no difference. I don't really smell any fuel. It's almost like it gets vapor locked. I tried to recycle the key on and off several times to pump fuel to the system. Didn't work either

[Scott65]

Have you tried pushing the pedal to the floor and holding it there while cranking? This should put the unit into "flood clear mode". This will offer a clue as to the too much fuel during hot cranking start.

[JLMounce]

If this is happening on a hot motor that has sat for 30 minutes to an hour and a half or so, what is likely is that the fuel film on the intake runners has evaporated. Cranking fuel is designed to add the necessary fuel to recreate the film on the intake runner and provide enough fuel to start and run the engine.

The fires, then dies symptom is usually a result of the priming shot firing the engine but there's not enough fuel to keep it running. There are however some other things that could effect this. Here's how I would troubleshoot.

1. Make sure that during cranking the system is seeing more than 10 volts. It takes more juice to start a hot engine, especially if you have a stock type starter. Check this while hot
2. Make sure the IAC (Idle Air Control) is set properly. With the engine warm and in park, it should read around 10 counts
3. Cranking Fuel is set either too high or too low. In your case, based on your testimony that adding throttle input does not help, leads me to believe the cranking fuel is set too low. IN small increments, adjust your cranking fuel upwards in your warm start area
4. Afterstart Fuel is set too high or too low. To set this, start the car and watch your AFR on the handheld. If the engine is struggling and running rough and the AFR's are increasing, you need more afterstart fuel. If the engine is choking and running rough while the AFR is decreasing, you need less afterstart fuel.

[Formulajones]

All good suggestions.

Like JLMounce said, the system needs at least 10 volts while cranking or it won't fire.

That would be the pink wire he is speaking of. That little 16-18 gauge pink wire needs to have 12 volts with key on, AND while cranking. Usually ran to the ignition switch.


Otherwise as Scott mentioned, it'll have to do with the prime shot or the cranking pulse shot while under the warmer conditions. So those tables will need to be looked at.

Generally speaking, if you pick the "street/strip" camshaft selection or anything beyond that to get your base tune loaded, the Holley tends to have overly rich start up tables. Picking a stock camshaft, as odd as that sounds, has start up tables that are more in line.

The 150 prime shot I generally don't have to mess with and leave alone. On hot cranking fuel I find that if it closely matches your lbs. per hour idle fueling then you're right in the ball park. Most engines generally idle with 10-12 lbs. per hour of fuel. So your hot cranking fuel, say 160 degrees and above, shouldn't be way above or way below that.

[stich]

I haven't messed with the handheld at all as I don't know anything about it other than plugging it in LOL. I may be able to find the screen that gives me these figures but not sure how to change them if I do. I do have full voltage while cranking. If I remember right, I picked the stock cam selection when I set it up. I'll check again on that. Thanks again for all suggestions.

[JLMounce]

Originally Posted by stich

I haven't messed with the handheld at all as I don't know anything about it other than plugging it in LOL. I may be able to find the screen that gives me these figures but not sure how to change them if I do. I do have full voltage while cranking. If I remember right, I picked the stock cam selection when I set it up. I'll check again on that. Thanks again for all suggestions.

As much as Holley, FiTech, FAST, MSD etc. what to claim these are "self learning" and "set it and forget it" type systems, they are not.

Take the time to sit down with your hand held and go through the product literature. Warm or Cold starting issues typically crop up as does tip-in fueling for most people.

Just like you can't expect an out-of-box edelbrock carb to be perfect on a Pontiac 455, you can't expect these things to be either. There is a learning curve, but it's not that bad once you sit down and go through the information provided by the manufacturer.

Start with your IAC and make sure that's set correctly, if you haven't. This is typically one of quickstart guide to-do's when first setting up the system. You can't get good startups, cold or hot without the IAC setup properly.

[Formulajones]

It's unfortunate but what JLMounce stated is true.

While there are some applications where it might plug and play and be fine, set the IAC and off you go, in many cases, some form of fine tuning is needed to really optimize the drivability.

In order to do that a laptop is needed.

[djustice]

I have had a very similar hot no start issue with my sniper, would run good but when up to temp the car shut off and i could not restart it til it had cooled off. tried a lot of roadside fiddling with power cables etc. but i found out that when i opened up the hood and took the aircleaner off the car started and ran fine.
if i tried to put either the aircleaner back on or even close to the throttlebody it would shut off instantly same with trying to close the hood without the aircleaner in place, car shut off.
Turns out the hood and aircleaner reflected emi down onto the ecu. but only when warm.
I closley examined the ignition wires and found a tiny tear in the insuation on one of the wires. swapped it out four an old cable i had lying and problem solved.

it migth be worth trying to take the aircleaner off and open the hood to see if it restarts when hot.

[Formulajones]

Something else to check is the accuracy of the coolant temp sensor. This is easily overlooked and I'm one of those victims.

The sensor supplied from Holley is notoriously inaccurate.

One easy way to check is when engine is cold, after sitting a couple days, turn on the key and compare the inlet air temp reading to the coolant temp reading. They should be nearly the same within a degree or 2. If you see a 10-20 degrees spread, replace the coolant temp sensor.

When I first got the Sniper, I did 2 installs on our own cars here, and both of the temp sensors ended up reading high by about 15 degrees. This really skews the cold and hot start tables as the engine isn't really as warm as the Sniper thinks. Before I had realized it I had already been doing cold and hot start tuning and ended up with completely out of whack start tables to compensate for what was a faulty temp sensor.
After I replaced the temp sensors I obviously had to start from scratch and completely retune the start tables.

[stich]

All good suggestions and will try again to see if anything works. Stay tuned. I have RAM air and a repo plastic air cleaner pan. I did put a Holly heat shield between Sniper and intake. Suppose to keep some heat from getting to the sniper.

[stich]

Thing just went from bad to worse. Now, out of the blue, I've developed a huge miss at about 2100 rpm. Still starts ok but after two tries or so. Then even after warm up, it's missing and popping out the exhaust bad. I changed out the plugs but to no avail. I'm pretty sure its electrical. But that's it. I believe I'll have to tow it to a speed shop that can diagnose and fix it. I think I should have stayed with carbureted and old points distributor. I could fix those back in the day.

[JLMounce]

It pops out of the exhaust during steady throttle or on deceleration?

Popping out of the exhaust during steady state throttle or during rpm acceleration would be really weird. Popping out of the exhaust is commonly caused by excess unburned fuel exiting the combustion chamber and reigniting in the exhaust pipes.

Does the AFR show rich when this is happening? If not, I would take a good look at where the oxygen sensor is installed and for any exhaust leaks upstream, or within 18 inches downstream of the oxygen sensor.

You didn't state whether or not you were running timing control. If you are, popping and missing may indicate that you have spark that is jumping terminals. This would be caused by the rotor and cap being out of phase. Consequently, this may also be part of a hard start issue.

[lfdsteve]

Fwiw I had a problem with my Powerjection unit. Don’t know why, but the problem started when I connected my vacuum advance to the port in the base of the unit (where instructions said to put it). Disconnected and capped that port and issue has never returned. Don’t drive it enough to try to find a work around so just don’t use advance.
Have no idea why but there ya have it.
Good luck

[stich]

Originally Posted by JLMounce

It pops out of the exhaust during steady throttle or on deceleration?

Popping out of the exhaust during steady state throttle or during rpm acceleration would be really weird. Popping out of the exhaust is commonly caused by excess unburned fuel exiting the combustion chamber and reigniting in the exhaust pipes.

Does the AFR show rich when this is happening? If not, I would take a good look at where the oxygen sensor is installed and for any exhaust leaks upstream, or within 18 inches downstream of the oxygen sensor.

You didn't state whether or not you were running timing control. If you are, popping and missing may indicate that you have spark that is jumping terminals. This would be caused by the rotor and cap being out of phase. Consequently, this may also be part of a hard start issue.

Pops on accerleration only No timing control, no exhaust leaks that I hear.

[JLMounce]

Originally Posted by stich

Pops on accerleration only No timing control, no exhaust leaks that I hear.

If the system isn't giving you any error codes, I'd start looking at your ignition. There may not actually be anything going on with the Sniper, it might be ignition related.

You should also check for vacuum leaks at the throttle body base and the intake manifold.