Help needed ASAP

[Jeff G 78]

I'll add it to the list Zed Head. Maybe Geezer will loan me his module so I can try it if needed.

[geezer]

I'll add it to the list Zed Head. Maybe Geezer will loan me his module so I can try it if needed.

Anytime Jeff. I've been really preoccupied as of late but will be glad to help if I can. Just let me know what you need. My dizzy and E12-80 module are known to be working well.

[Jeff G 78]

How have you been Ron? I hope you've had so time to work on the Z. I'd love to borrow your module. My dizzy is working great and hopefully the module is as well, but it would be nice to rule them out just in case.

[Travel'n Man]

Jeff-

Remember that you will need a block off plate for that mech fuel pump - they are still out there if you order one from your local Nissan dealer. Once you get your dyno numbers let me know what they are and let me know the type of dyno your car is getting dyno'd on. I just had mine dyno'd earlier this month - not any crazy numbers due to not jazzing up my cam to a higher stage number but all is good. I've got all the power and torque I could want for my needs.

Sounds like your fuel delivery system is going to be great - be sure to get your best filter closest to the tank! i did put an in-expensive glass one between the fuel pressure regulator and the fuel rail. My fuel pressure gauge is in my engine bay - be careful where you mount that since you do have live fuel running through it.

Safety fire extinguishers are a must for any racer at any level - IMO

[Captain Obvious]

That sounds like a great plan. I sure hope you find the issue!!

Couple of quick comments before it's too late...

Why are you going to remove the mechanical pump? The 260 originally had an electrical pump in back feeding the mechanical pump up front. And, just because you're not using it, doesn't mean that the pump has to come off the side of the block, right?. You could leave it in place and plumb around it. You could even get fancy and pipe the outlet back to the inlet!

But if/when you do remove the mechanical pump, you should be able to easily fashion a block off plate out of some sheet steel or aluminum. There isn't anything complicated about the shape. Flat works fine. Cut to rough shape, drill two holes, cut some gasket material, smear some goop, and you're done. I'd hate to see you spend out of your $500 for something like that!

And... If you're going to put a thermostat in, you should probably have a working temp gauge.

[Jeff G 78]

I do have a block off plate on a spare 280 head, so I'm good there. I might leave the mechanical pump in place for now though until I get an idea of what's going on.

As for the temp gauge, I'll have to diagnose it if it still doesn't work. The sensor and gauge came from a '75 that I parted out. The gauge worked 20 years ago when I quit driving it. :-)

Oh yeah, we always have an extinguisher in the car and ready to use.

[Captain Obvious]

Cool.

So... What happens if all the investigation into fuel delivery doesn't turn up the problem? How can you tell if the fault is actually ignition, and not fuel delivery? Other than shotgunning it and replacing modules to see if that makes any difference, is there any other diagnostic work ahead of time that can be done?

I've done no work with the Z ignition to date, other than plugs, wires, caps, etc... maintenance stuff. Thankfully, I've never had to do any diagnostic work, and consider myself blissfully ignorant.

Maybe the spark is timed correctly, but doesn't have the strength to fire through the densest gasoline cloud that occurs under your problem conditions. You wouldn't see it under light load conditions. Could rev fine all the way to redline while sitting still, but might not work so well once on the track and you're pulling all that fuel and air into it?

I'm not trying to be pessimistic... Just thinking about contingencies now because once you're at the track, it's all willy-nilly fire drill, right?

[madkaw]

So are you going to change around pumps before rechecking or richening the floats?

[Jeff G 78]

Steve, My plan is to return the needles to the correct heights first since that's the way we ran it Sunday prior to my experimenting. I will then CHECK the fuel height in the nozzles. If they are WAY off, I might have found a cause, but I doubt they will be off by much. I made myself a float height gauge block last year and that's how I set the levels. My SU's are from a '72 so they have different float heights front to back.

Here is the block I made per the FSM. It makes setting and checking the floats WAY easier.

Captain, Unfortunately, it will be fire drill time at the track, but with the right planning, I will have a pile of parts to try and a specific order in which to try them. If NOTHING fixes the problem, then we simply become a rolling chicane for 25.5 hours and I will be very bummed.

BTW, we have also tried different wires, cap/rotor, and plugs. The spark we have is very strong. When we did a compression check and I pulled the coil wire, the spark was jumping well over an inch from the coil wire to the body.

[Jeff G 78]

I never heard back from Black Gold Man on the RX7 pump, so I stopped today at Napa and bought both Facet pumps. I am still confused about which one is the better choice. From what I understand, the SU's want 3 - 4 psi right? The Facet pumps are 1.5 - 4 psi and 4 - 7 psi. The higher pressure pump flows about 10% more as well. So what exactly does a pump's range mean? Is the 1.5 - 4 pump going to be too low of pressure?

I tried but failed to find a regulator locally, but I got a lead from the guy at Napa of a race shop in town that might have them. I'll check tomorrow. If I find a regulator, the higher pressure Facet pump should be better and then I can adjust the pressure down, but if I don't find anything, which should I use?

[Travel'n Man]

If you'd like to talk to him call me and I'll give you the number at the shop. 503-587-9800

Jeff -

I believe Bruce would know exactly what to set that pressure at - my Mikuni's are set at 3.5 psi. Pressure regulator is a must in my opinion. Best of luck. Let us know on that dyno once you get it finalized.

[Captain Obvious]

Don't you hate ambiguous specs. I did a little digging and came away more confused than when I started. I don't know for sure what those numbers mean...:mad:

What are the part numbers for the pumps you bought?