I read through a few threads concerning non-starting FDs, but I just wanted to bounce some ideas off everyone before I started tearing into stuff and replacing stuff.

I've had the car for a year now, never had a starting issue. Was bone stock when i acquired it. It is slightly modified now.

Some Mods.
PFC, Dual Oil coolers, koyo rad, blitz fmic, hks twin power etc etc.

Most Recent Mods before starting issue.
Changed Spark Plugs
HKS Twin Power
Aeromotive Stealth Fuel Pump /w Hyperion Fuel Baffle
AEM Meth Injection 25% Meth 75% Distilled Water

I drove the FD exactly one week ago, started fine drove perfectly fine also. Brought it home, parked it in the garage for one week and tried to fire it up today and it would turn over strong, but wouldn't start.

My most immediate thought is that it's not getting fuel. That being said, When i replaced the fuel pump I didn't do the relay mod or rewire it. Could the Aeromotive Stealth fuel pump screw up the stock relay/wiring ?

Thanks
Scott

 

I've read of some people wiring the aeromotive stealth pump backwards, apparently the pos and neg are opposite of Walbro, but I would assume you got it right since you drove it a week ago.

 

yea, drove it about a week ago and took it to streets of willow about 3 weeks ago. ran perfectly fine at the event and afterward.

just saw some photos of theorie's melted fuel pump wiring, might try to pull the fuel pump cover off real quick when i get home to check that.

 

^ while you are at it check to make sure the pump is running and pumping fuel. Have you checked for spark?

When you tried to start it last did the engine fire at all, or is it cranking over like the ignition is off?


John

 

I haven't checked for spark yet. The engine didn't fire a single bit this morning. Just kept turning over.

If there was a little bit of fuel left in the lines it should have at least turned over then died then right ? Are you hinting that maybe spark is the issue ?

 

What rpm is it cranking at?
Have you deleted the clutch switch and security relay?
Just to be sure you checked the battery %?
Got a fuel gauge to check psi?

 

wasn't staring at the rpm gauge when i was cranking, unfortunately.

haven't deleted the clutch switch or the security relay. what does the security relay do ?

battery was fully charged, put it on the trickle charger before i left for work.

I don't have a fuel pressure gauge = (

 

Security relay is known to rob power from fulling activating the starter, typically though it wont crank at all. Same with the clutch switch:

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/one-possible-fix-click-click-start-problem-remove-oem-security-relay-872841/

 

Got it, I think we can rule that out then. Although my miata constantly does that to me right now.. haha.

 

Take the fuel pump out and triple check that is installed correctly,this happen to me but my car would start with bad idle, the fuel pressure was at 20psi.

 

I installed the fuel pump and baffle prior to going to a trackday and i didn't have any hitches in my giddyup while there, but this is now 3 weeks later. driving me up a wall right now since im at work = /

 

Yes, or your injectors are not working at all for some reason.

I would check for spark first, and check fuses, then go from there.


John

 

I think we might be over thinking this a little bit have you done any deflooding procedures? Crank the car if it doesn't start take the plugs out they should be drenched in fuel (if you are getting fuel) if they are bone dry then you are not getting fuel.

 

I've flooded my rx7 before and it usually will sputter or something while trying to crank over, but this morning it didn't even sputter or attempt to crank at all, but I will add testing to see if its flooded to my check list.

 

Just went home for lunch and pulled the fuel pump to check for melted wires or anything else that looked funny. Everything in the tank was in order, wires didn't look overheated or melted or charred.

Only funny thing was that the new filter screen that attaches to the aeromotive pump fell off. Found it down inside the baffle tank and reinstalled it. Could the filter falling off have allowed a lot of gunk to get sucked up and plug the fuel filter ?

Didn't have time to mess with spark or the fueling inside the engine bay.

 

Just got home and jumped the fuel pump with the key to the on position. I don't hear any buzzing or anything from the trunk. I also jumped it and took a multimeter back there, highest voltage I got off the plug testing random ones was 6volts? Is something fishy?

Also noticed the Rpms don't jump at all then I try to crank the car.

 

U need to rewire asap. I have the same fuel pump and i believe the instructions say that rewire is a must, in order for the fuel pump to function correctly. The rewire diagram is in the instructions. I get 13.0V at the pump. I don't think the pump would even come on with 6V.

 

try putting back on the old pump and see what happens? or would the wiring already be fubared?

 

12V, directly from battery to pump with a decent wire, and see if it pumps. If not, use a heavy wire to wire to ground to chassis properly, if there is no life then when giving it 12V, pump is crapped! dont need to dismantle the whole shabang to see if pump is dead.

 

figured i'd update the thread. got to work on the rx7 this past weekend.

due to the low voltage to the fuel pump and the non-existent rpm bounce while cranking I thought it was a ground related issue. so before i started messing with cranking the car over again i went through all the grounds (or the ones i could find at least) and inspected/repaired or replaced them. a couple were pretty corroded looking to i replaced them and also scuffed up the areas they were mounted to ensure a good contact.

tried to crank the car.. and it was completely dead... left the doom light on overnight = /

swapped out the miata battery and went to try a few more things before cranking. jumped the fuel pump and measured the voltage to the pump. 11.98 volts ?! hmmm

pulled a spark plug stuck it in the cable and had my gf crank the car. strong spark on each rotation ?! hmmmm

pulled one leading plug on each rotor and put a compression tester to each one. three consistent high pulses on each rotor ?! hmmm....

this was all leading to me thinking the car was alright now... so i tidied up the engine bay, got the car off the stands and decided to give it a try...

three cranks and it fired right up like nothing ever happened... ?! absolutely puzzled and thrilled at the same time.

My friend believes that my car was flooded and maybe it was a leaky injector, but I don't know. when i pulled the plugs they weren't drenched in fuel at all, so im not entirely sure if it was that or whether cleaning up my grounds was the fix. either way I have a happy running rx7 again which is all that mattered to me.

Thanks for the help everyone.
Scott

 

glad you got it fixed. i have had flood issues before, the spark plugs were not wet. so it most possibly could have been that.

We have had some really cold So Cal weather so that makes sense.

 

Sound like it was flooded. Was it trying to fire at all when it was down? The act of removing the plugs and performing the compression check could have resolved the issue for you.

 

didn't try to fire at all when i was cranking it. you guys are probably right, just a flooding issue = /

at least i can laugh about it though.. haha