J-Rat

iTrader: (2)

I have tried everyting..

The problem has been in the same car, with 2 motors now. The motor in the car was from another car that didnt have this problem. As soon as it was installed in my car, the hot start problem was there, as well as for the previous motor.

Things changed:

AFM
ECU
BAC
Injectors (to another set of used ones)
Compression test (good)
TPS

I am going to order new injectors, thats the only other thing I can think of.

So, has anyone solved the problem yet?

Jarrett

hypntyz7

I know you dont wanna hear this, but a rebuild always solves the problem. Flooding/hard starting is, IMO, a compression problem more than anything. However, I see your point that you believe it is something else since it only happened during an engine swap. Out of curiosity how long did this engine sit unused between swaps?

J-Rat

iTrader: (2)

The motor was taken out of the donor car, and swapped in less then a week. It only happens about 30 mins-2 hours after its shut down..Anytime before or after, it starts right up.

Rat

tweaked

iTrader: (4)

I did it with two motor @ or above 85K. clean all of the intake parts. change your fuel filter. get your injectors cleaned. make sure your air temp and wanter temp sensors (for the ECU) are working with in spec. and this was the final step, buy an MSD 6A or 6AL. this has made starting the cars easy as hell. hot or cold. it helps performace too. you only need one on the leading coils. MSD will tell you to get three. One for the leading an two for the trailing.
do the other stuff first. this will help the overall perfromance and reliability of the car too.

Turbonut

iTrader: (1)

Jarrett:
With a good motor/good compression, and as long as FPR is mantaining correct pressure, I think it's an injector problem. As pressure builds after shutdown, a small amount of fuel must be leaking into the chambers. That's why a lot of people use the fuel cut switch as a band-aid. I have even seen the "H" fitting that goes between the fuel feed and return line. As pressure builds after shutdown, the fuel is routed back to the tank, rather than into the motor.
This may be long, but years ago I had a Chrysler product (carbureted) that did the same thing.Couldn't stop the hot start "flooding" after shutdown. I adapted a fitting with a small ofice in the feed line and connected it to the return line. Not one more problem.

yearrgh

I still had the problem after an engine swap. I took it to mazda (yeah, yeah, bad idea.....there's a reason behind it) They kept it for an extra week because of the hard start, as well as the "revving idle" problem. They said it was electrical, but I think ambient temp affects it somehow since the problem is worse for me when it's hot out and when they finally "fixed" the problem, it was an unseasonably cold day. the next day was hot and the problem came back

J-Rat

iTrader: (2)

I wonder if anyone has tried this before...I am trying to think of what it would do to the fuel pressure...

jarrett

J-Rat

iTrader: (2)

Good ideas!! I will test all the sensors. as far as the 6AL, I am not going that route, I am selling the car!

So your ideas ended up solving the problem?

Jarrett

j9fd3s

iTrader: (3)

my problem was vacuum related, the acv needs to have the hoses correctly routed, so the fix on my car was, NO VACUUM LEAKS, it had 160k mile injectors too

mike

NZConvertible

Everyone with unsolvable hot-start problems should read this thread.

J-Rat

iTrader: (2)

Yeah, I read the article from akageals, but he spoke up later in a thread and said the problem was back. I have already swapped the ECU, although I have yet another one I can try. Here is something that TURBONUT sent me...Looks like I might give it a shot:

INJECTION FUEL PRESSURE BLEED-OFF (86-92)

We continue getting a number of cars (86-92) in our service department (and many phone calls) with leaking fuel injectors. The main symptom is flooding after the car has been sitting for a few hours. It can manifest itself after running for as little as a minute or two! Basically, if you try to re-start the car anywhere from a few minutes, to a few hours later, it just will NOT start. The "no-start" is usually OK after sitting for the night.
The injection systems hold residual fuel pressure for many hours after the engine is shut off, and if an injector is leaking, it will simply drip fuel in the engine until the pressure has stopped. This part we have assembled should be considered a temporary fix, or a diagnostic tool only, because it is not going to fix the root problem. However, it can get the car back on the road for a lot fewer $$ than new injectors. Plus - it is hard to find out which injector(s) are the problem - you have four!
It is installed in-line where the fuel supply and return lines attach to the engine, below and forward of the oil filter. There is a very small jet inside the "H" that allows the residual pressure to bleed back to the tank, thereby preventing the pressurized dripping past an injector.
----- The Kit includes the fuel lines and clamps needed, plus installation instructions. -----

Part Number 13-MZ-BLEED

Don


I am going to run all the BAC tests first (signals, etc..) But I suspect that the BAC is barking up the wrong tree.

Jarrett

HAILERS

Well, if it were a fuel problem requiring the H fix..........You could prove this is/is not the problem just by pulling up to the driveway, turning your fuel cut switch to the off position, and letting the car die. So now there is no fuel pressure in the fuel rail or anywhere else. Now turn the key to off. Go sit for whatever time you want. Then go start the car with the fuel switch in the on position.

Fuel injector cant leak if there's no fuel pressure. Note: I did not read the last five or six posts above your last post, so if that was suggested........

CaR 13

i changed my fuel filter and when ever i run the car hard i let it sit for a little bit afterwords like it was a turbo and i have never had the problem sense

J-Rat

iTrader: (2)

LOL!! Good suggestion, and tried. If I use the switch to shut the car down, there are NO problems restarting, at any time.

Ordinarily, I would be happy with this, but I would like to sell the car. I have personally done over $2500 worth of work to this car, and would like to sell it for $2000. HOWEVER, its doubtful I would get that amount of money, if I had to expain to the new owner about the finer nuances of a fuel cut-off switch. (unless of course the new owner is an RX-7 person, which around here is doubtful.....)

Jarrett.

J-Rat

iTrader: (2)

I am definately going to try that too, reason being, I believe that some of the residual fuel pressure is leaked back to the tank via the fuel supply line. I may be way off base, but it seems that a clogged fuel filter would inhibit the bleed-down of pressure through the filter.

Thats my "way out in left field" theory, and please anyone feel free to dispute it.

Jarrett....(****..its gotta be the flux capacitor)

Turtle's TII

I have gone through all of this same BS. I went through everything. I think maybe a new ECU from Mazda might do the trick.

Before you think it's a leaky injector, make a tee to put into your inlet line, and put a FP gauge on it. Run the car while HOT, shut the car off. If the pressure bleeds down, it is possible the injectors are leaking. My pressure held steady for hours. But I pulled the injectors and had them professionally cleaned anyway. And it did not help.

I went through everything I read about online, and nothing helped. I even bought one of those Anti Flood Modules, it did not help. I was not going to give up and install a fuel pump switch. "It has to be something" so I dug deeper.

I finally, after a year or more, broke down and did the fuel pump switch. And it worked.

I still think that Mazda had a bad program in the ECU, that added too much fuel on hot start, almost like it added cold start fuel everytime you cranked the key. I have even had it stall, and not want to fire in a carwash, rolled it out, barely rolling popped the clutch, and it fired right off.

So I think the cranking mode adds too much fuel, maybe even cold start fuel everytime. I even jumpered the coolant temp sensor so the ECU would think it was 300 degrees, and it still added too much fuel.

So this is my theory, but I'll be damned if I will buy a new ECU from Mazda. Save your money and time and buy a switch. Even if you are selling the car, just sell it with the switch.

PS I had 95psi on all sides of both rotors.

J-Rat

iTrader: (2)

Only problem I am having (aside from the hot start!), is that I cant seem to admit defeat.

But you do make a good point. And the information is good, thanks!

Jarrett