[dankwen]

I'm troubleshooting my 76 CJ-7 with an AMC 304 V8 and could use some help. This Jeep is new to me, and on my first long drive she died on the side of the road.

Symptoms and event rundown:

• Once she was warmed up RPMs would drop and sputter at lower RPMs or idle.
• I could work around it for a while by dropping to neutral and giving her some gas, but eventually that stopped working and she just went dead as I was coasting to a stop.
• She cranked a couple times but no catch. Eventually stopped cranking.
• After about 10 min a jump got her going again, but she died again a few miles later.
• After about 3 hours on the side of the road she cranked up and made it home just fine (~15 min drive).

My first thought was a bad alternator and a low battery to where it couldn't support a spark, so that 3 hours on the side of the road I spent pulling the battery and taking it to the closest auto parts store. They checked the battery and it wasn't low or dead. They topped it off and when I reinstalled the Jeep fired right up and I made it home.

So I don't know if this is a a fuel problem, a tuning problem, or a heat problem since she ran fine when she started cool.

PO added a Holley Sniper but I didn't get a manual. Anyone familiar with that unit? Could this be a tuning issue in the Sniper EFI?

Symptoms also seem to match a worn out and hot Ignition Control Module, but I don't know if the Sniper EFI system replaces that part... anyone know?

All other ideas greatly appreciated!

 

[Rkuehljr]

The Holley Hyperspark that the Sniper would control is an option, so unless you see a black box that says Hyperspark on it, it probably isn’t. pictures Will help

 

[ChrisReyn]

PO added a Holley Sniper but I didn't get a manual. Anyone familiar with that unit? Could this be a tuning issue in the Sniper EFI?

I am planning the Holley installation on my 304, and based on what the Holley techs have told me, IF the PO installed the correct model for the 304, it should be the 2300 model. Heres the manual for it. The mini-screen can give you a ton of info about whats going on with the engine..
https://documents.holley.com/techlibrary_199r11321.pdf

Hope this helps..

 

[dankwen]

The Holley Hyperspark that the Sniper would control is an option, so unless you see a black box that says Hyperspark on it, it probably isn’t. pictures Will help

Yep -- there are 2 boxes that have Hyperspark on them. Here's a pic:

 

[dankwen]

I am planning the Holley installation on my 304, and based on what the Holley techs have told me, IF the PO installed the correct model for the 304, it should be the 2300 model. Heres the manual for it. The mini-screen can give you a ton of info about whats going on with the engine..
https://documents.holley.com/techlibrary_199r11321.pdf

Hope this helps..

Thanks for the reply. Hmm... my fuel injection unit looks different than the 2300. Looking at the Holley site I think I have the 4BBL.

 

[ChrisReyn]

Thanks for the reply. Hmm... my fuel injection unit looks different than the 2300. Looking at the Holley site I think I have the 4BBL.

yea, that looks like thepart #550-510 unit.. And yes, that looks like it is the Hyperspark ignition system.
https://documents.holley.com/techlibrary_199r11031r-1.pdf-- the EFI manual?

https://documents.holley.com/199r11369.pdf-- trouble shooting guide for the Holley EFI

 

[ChrisReyn]

there might be a part or model number printed on one of the "ears" at teh base of the unit , something like this:

 

[Rkuehljr]

What do you know about the fuel pump? Did the PO put an in tank pump in or is there an external pump mounted on the frame rail, near the tank? Is there a fuel return to the tank? One is not necessary with in a tank pump that has pressure regulation. Is there a fuel pressure gage? It should be 60 psi. Just grasping at some of the basics.
You might want to check on the Holley forums.

 

[Matt1981CJ7]

I know nothing about the Sniper/Hyperspark system, but isn't there some sort of data-log that you can run to help you troubleshoot problems?

Matt

 

[dankwen]

What do you know about the fuel pump? Did the PO put an in tank pump in or is there an external pump mounted on the frame rail, near the tank? Is there a fuel return to the tank? One is not necessary with in a tank pump that has pressure regulation. Is there a fuel pressure gage? It should be 60 psi. Just grasping at some of the basics.
You might want to check on the Holley forums.

Good question... It's been about a year since I had it running so I'm going from memory, but I think the Sniper computer displayed the fuel pressure and it seemed fine, no change when the rough idle would happen.

About the fuel pump, I don't know what the PO did so I rolled under and grabbed a couple pics. Looks like there is a return line. I think that last pic is the fuel pump, and it looks like it's grounded to the fiberglass tub... I'll run a ground to the frame and see if that helps.

It also looks like the fuel line makes a big loop that kinks it a little before going into the filter. I'll see if I can do something to improve that.

 

[dankwen]

I know nothing about the Sniper/Hyperspark system, but isn't there some sort of data-log that you can run to help you troubleshoot problems?

Good thought, thanks. I'll have to look at this and see. Still need to dig into what the sniper computer logs.

 

[pedal2themetai]

Hi,
How hot did it get?
is that fuel filter near the carb or is it under the Jeep? It needs to be up top close to the carb (OOPS injection) so the fuel can keep cool all the way to the injection with the return line on top 12 o'clock position
so it could be heat related??

good luck take care be safe
tim

 

[ChrisReyn]

The one close to the tank, between the tank and the pump should be the primary filter, you want to filter the fuel before it goes through the pump.
The pump should be mounted on the frame, below the level of the tank or as low as you can get it. It should ideally be 3/8" hard lines from yjr filter to teh pump then to the engine compartment. Too small of a line or a clogged filter, or a bad pump could cause fuel issues that might result in your symptoms. It is recommended by Holley to mount a fuel pressure gauge right before the EFI unit to monitor the pressure the unit is recieving.
A collapsed or under sized return line can also cause pressure issues

 

[ChrisReyn]

Note Item 3 in teh flow chart for trouble shooting the EFI

 

[John Strenk]

Good question... It's been about a year since I had it running so I'm going from memory, but I think the Sniper computer displayed the fuel pressure and it seemed fine, no change when the rough idle would happen.

About the fuel pump, I don't know what the PO did so I rolled under and grabbed a couple pics. Looks like there is a return line. I think that last pic is the fuel pump, and it looks like it's grounded to the fiberglass tub... I'll run a ground to the frame and see if that helps.

It also looks like the fuel line makes a big loop that kinks it a little before going into the filter. I'll see if I can do something to improve that.

View attachment 4179388

Are you sure it's a Fiberglass tub? If so, that pump would never run with that ground connection.
But still, those external pump are know to fail a lot. One of the reasons I put the fuel pump in the tank.
It could of over heated and then cooled down later.

You can solve a lot of mysteries with a inline fuel pressure gauge. I'm not quite sure where to put it on the 4bbl Holley Sniper.