donsz

I researched the prior threads on this issue, a lot of good information, but didn't find any resolutions. This seems to be a "painful" problem. I'm afraid to take it to the dealer, I visualize
thousands of dollars spent on parts swapping without any real insight.

I have a 1985 GSL-SE (original owner) with 26K miles on it. Recently, after the engine warms up to operating temperature, the engine cuts out at high rpm.
Depending on the time/temp, it stars at 6K and eventually cuts out at about 4K.
What I have done:
- Replaced the fuel filter (didn't expect it to fix it, but a was a simple first step)
- Replaced the air temp sensor at the RE-EGI housing
- Replaced the water temp sensor at the water pump
- Took out and cleaned the FC air temp sensor ( p/n N236-18-845A), which seemed really clean anyway)
I can't find a replacement N236-18-845A, or N326-18-845 except in Canada. But the company doesn't ship to the US). The sensors are on some other sites, but these sites seem
very suspicious.
- Checked various sensors using they ohmmeter. Checks specified in the service manual (throttle positioning, etc.) All checked good, but they were done with the engine cold.

It seemed when I took out and cleaned the FC air temp sensor, the engine operated normally for a longer period of time. Normally I could just let it idle to operating temperature
and it would exhibit the fault. However, after the cleaning of the FC air temp sensor, I had to drive it for about five minute (after it was warmed up), to make it fail.

Anyway I am quite perplexed about this, and wonder if there is any new insight on this problem. Also, where I might get the n236/n326 or N326-18-845 part. At the point
I would try and replace it even though it visually looks good. This has really taken the fun out of having an RX7.
Thanks
don

-

KansasCityREPU

iTrader: (9)

Have you checked the 5th and 6th port actuators? If they are not working you will get a power loss (or no gain) at 4K. I'm not a GSL-SE expert. Here is some more info.

https://www.aaroncake.net/rx-7/6portfix.htm

donsz

I'll double check, when I looked, the actuator rods were moving at high rpm. But that was at startup, not operating temp. I will check them at operating temp. Good link.
Thanks,
don

Seniorchief

Actuators will only open with backpressure, revving the engine will not open them. An easy check is seeing if you can manually open them, if not, put some grease on the actuating rods and take it over 4k rpm for a few gears and then see if the grease has been pushed up the shafts.

LongDuck

When you say that the engine "cuts out" what does that mean? Loses power? Shuts down? Recovers at lower RPM?

Start there, and describe what it does when you're driving it (*use terms other than "cuts out"). Be patient, we've all been where you are when you hate driving the car you once loved...

donsz

I'll try to be more specific. I'm not 100% sure what is technically happening. It feels like the engine is "shutting off" at high rpm and when you let off the throttle it revs as normal in the lower rpm range. It seems like either it gets no gas or the electronics (spark?) is not present at higher rpm. Above about 4k nothing happens as you press the throttle further except a "jerk" during acceleration as the non-response rev limit is encountered.. Again, this only happens when the engine is at operating temperature. I hope that helps.

I did get some "spray freeze liquid" that once the engine is warm, I will try to target and cool down down affected sensors. I'm not sure what that will really prove, except maybe give me a start. If it is the sensor near the 5 & 6th port actuators (N236-18-845A), it appears that that part will be hard to get. And KansasCityREPU, I will do the check you suggested.
Again Thanks,
don

LongDuck

First off, avoid the stealership; nobody there is going to know anything about these cars, and if you find a service writer that takes it on, they'll do more damage than good. On top of that, you'll be paying high costs for them to "learn" on your car. Don't do it.

As for the problem at hand, I would focus on these 2 areas, and in this order:

1) Fuel - You said you changed the Fuel Filter (*hopefully with OEM, and not some cheap plastic garbage), but the Fuel Pump is very old at this point, but not necessarily a problem. You'll need to check Fuel Pump flow to the FSM, as what you describe could be due to a pump that can't keep up with fuel demand at speed. If not the Pump, there is an inlet cone filter in the Fuel Feed line going into the Fuel Pump. If this is clogged, it could result in a restriction that will cause fuel starvation. Additionally, inside the Fuel Tank is a sock filter over the end of the Fuel Pickup. Same potential issue - any clogging or particulates in the Fuel Lines or feed mechanism could lead to starvation at high RPM and particularly under load. Look for any leaks in the system, and might be worth removing the rubber fuel lines and blowing out the feed and return lines to be sure nothing is in there. While you're at it, look for any damage or dings to the metal lines under the car; if one is crimped, it will significantly reduce flow and volume. Lastly, inspect the Fuel Pulsation Dampers located at both the Fuel Pump junction and at the Fuel Rail to be sure they're not leaking. While rare, if a pulsation damper has gone bad, it may be causing hydrostatic frequency vibrations in the Fuel Rail which are working against the Fuel Injectors. Lastly on this, recognize that the Fuel Pressure Regulator is on the other end of the Fuel Rail and high engine intake vacuum shunts the return line, bumping Fuel Pressure to meet demand under load; check the vacuum connection from the Fuel Pressure Regulator to your vacuum hose spider, and from there to the upper intake plenum.

If the engine can rev to high RPM sitting in your driveway, I'd tend to suspect fuel starvation caused by one of the above issues, possibly several in conjunction.

2) Ignition - If your fuel system checks out according to the FSM, then what you describe could be caused by a failing Ignitor (*Leading or Trailing), Coil (*Leading or Trailing), bad spark plug wires or bad spark plugs. In order, the Ignitors (*Leading & Trailing) are located on the Distributor and can occasionally fail, usually due to heat, and usually progressively worse over time. These can be swapped to check function, as the engine will run on Leading ignition alone, but not on Trailing alone. The ECU takes its RPM for the Tachometer from the Trailing Coil, fired by the Trailing Ignitor. Without a working Trailing pulse, the ECU doesn't know when to fire the Fuel Injectors. Point being, if your Trailing Ignitor is going bad and overheating, it could result in the ECU shutting down Fuel Injector function at high RPM. If this is the case, swapping Ignitor position will tell the tale. Anything else which is required to send that ignition timing signal to the ECU could be causing the problem, i.e., the Coils or the wiring in between.

If you've not done so recently, replace the Distributor Cap and Rotor, your Spark Plug Wires (*and Coil connection wires) and put in new BR8EQ14 plugs, leading and trailing. Spark Plugs are consumable items for our cars and should be checked at every oil change and replaced after every 10-15k miles. These are the simple, easy tune-up items, but I'm hoping you've already got this base covered.

Post back. We'll figure it out,

JNew

Interestingly, a new reply to an old thread (https://www.rx7club.com/1st-generati...robelm-763139/) just popped up about an -SE that would idle fine but choke when driven.

The crux of the problem was a clogged pickup tube in the gas tank. While the FSM procedures for fuel were followed, everything checked out, particularly the fuel pressure. But it was pointed out in that thread that the FSM doesn't have a fuel volume test. When that was done, it was shown that the fuel volume was very low, causing the condition.

So, to build on LongDuck's great troubleshooting advice, check out the thread mentioned above and realize that fuel pressure and volume should be checked.

donsz

Thanks for all the great advice. My gsl-se only has 27K miles on it, I have never checked the spark plugs. I don't know if they are the problem, I took them out and they don't look good at all. So, I'm going to order the spark plugs and then if that doesn't resolve the issue, I'm going to continue with the suggestions provided. I'm a little hesitant about the gas delivery issue because it works fine when cold. However, there may be something to that, since when idling (hot or cold) it does seem to have a little "miss." I will update this thread with my progress. I really appreciate the responders taking the time to provide their insights. There is real expertise on this forum and frankly I don't know where else to turn. I even checked with our local dealer, and they said they didn't have the expertise in-house to deal with the problem.
So, thanks for all your excellent advice,
don

LongDuck

IF these are the original spark plugs, that's probably the entirety of your problem. Spark Plugs MUST be changed regularly, as the ignition systems on these older cars are BARELY powerful enough to fire when everything is new (*plug wires, distributor, rotor, etc.).

I'll bet when you change the plugs, that first drive is going to bring back the love!

donsz

Update: I have ordered the correct sparkplugs and a new distributor cap. I couldn't find the BR8EQ14 plugs locally, so I ordered them from an on-line supplier.
Again I appreciate all the input and when I get the plugs and install them I will provide an update as to the outcome
don

LongDuck

Regardless of the outcome, PLEASE post back and let us know what fixed it. You wouldn't believe how many threads around here just drop off a cliff and lose so much value to future searchers.

While the Bosch L-Jetronic fuel injection of the Series3 GSL-SE is very simple and reliable, the age of these cars sometimes brings on issues due to age that require some insight. Good luck with the plugs. I hope that's the easy fix,

donsz

I changed the plugs and distributor cap, runs smoother but still cuts out and can't make full rpm. I notice that if I stomp on the gas pedal the the loss of engine power starts at 4K rpm and doesn't want to go much higher. When i "goose" the throttle at fast intervals, I can coax it to reach the rev control warning alarm (7K). The 5 and 6 actuator rods do seem to fully move to full extension when I "goose" the rpm. Now I'm beginning to think a gas delivery problem. Note: the gas in the tank is from last year, and I don't remember when I filled it up. I usually drive the vehicle less than 300 miles a year (for the last 25 years). but I have never had this problem before, so I'm not sure if the quality of the gas is an issue.
don

donsz

Thought I would update this since it is a vexing problem and many have taken the time to respond. I got involved in a project and haven't got back to this until last week. Based on some advice from Mazda mechanics, I found an used air flow meter and installed that. Unfortunately, it ran much worse than before, even when cold. So, it could be the air flow meter or not. It may be, mine was actually OK and the used one was defective. Which would prove nothing. Or. since the used air flow meter had such a detrimental effect, it at least identified that was the problem area. In any case, I ordered a new one (the used one wasn't very shiny anyway). It should arrive in about a week. I'll install it and report back.
again. thanks,
don

LongDuck

Well, it's been 4 more months of frustration, and I'm sure you're wanting to get this car back to running properly. I noticed in rereading the thread that you tend to focus on the electronic or electrical parts rather than the mechanical. Is here a reason for that?
Our advice before was to do a basic tune-up of the Distributor Cap & Rotor, Wires and Plugs. You did the plugs because they're original to the car and almost 40 years old. Did you perform the rest of the tune-up? Why did you change the ﹰAir ﹰFlow ﹰMeter? Did you test somwthing there and it was showing out of spec?
ﹰOftentimes, when we're trying to fix something, we lose track of the basic, simple things under the belief that it must be more complicated than it is. Case in point, I have 250k miles on my 2-owner SE and there are so many original parts (*ECU, sensors, etc.), that it's easier to list what I've replaced rather than what was on it when it left Japan. My point is to focus on the simple things - the basic things - that the car NEEDS to run well, and I'll bet it's something simple.
Let us know how it goes, and stick with it,

donsz

Sorry I left everyone up in the air about this, still no remedy. It still runs great when cold, but once it reaches operating temperature it cuts out at about 4K rpm.
I have been reluctant to post about my lack of progress, it seems like I'm just throwing parts at the problem now without any real insight.
- Since last time, I have replaced the coils and ignitors, no change.
- I removed the air temp sensor (N236-18-845A) and examined it, it reads about 29 ohms @ 45 degrees F, however, it looks very clean and undamaged.
Even so, it doesn't look like they are available, including the N326-18-845 replacement (2nd series sensor)

I'm thinking about replacing the fuel pump next (fuel filter has already been replaced). Although I'm not sure why it would wait until operating temperature to malfunction
(or maybe it is a function of time not temperature, with temperature being a red-herring). The fuel pump is not cheap though, I would get the direct replacement.
And yes, Long Duck, I guess I do focus on the electronic elements (a former aerospace tech), and I guess I'm used to temperature a electronic components not mixing
well at times. I really do appreciate your well thought out comments, as well as the others.
don

LongDuck

Good to see you back. What exhaust system is on the car? Could be a red herring, but you should not see the 6-port Actuators move when free-revving in the driveway. Those require 4-6psi of volume air pressure to operate and that only happens under load. Let my brain work on your latest note for a day and see what I can come up with,...

LongDuck

Bumping your thread, hoping you'll see it.

If the engine cuts out at 4k RPM in every gear and under load, that failure is consistent with a clogged Fuel Filter. I know this because I just had those symptoms yesterday due to sediment in my Eagle gas cans getting into my fuel system. I replaced the N-304xxx EFI Fuel Filter and back to 100%.

I know you just changed it, but if it's sediment from a rotting fuel tank, it's a quick and easy fix to verify. Good luck,

donsz

Thanks for your continued help and attention on this. I did replace the fuel filter, there was no change (although a contaminated tank could be possible).
Update:
- New air flow meter installed, no change
- O2 sensor (cheap shot in the dark) installed, no change
- Removed and inspected the n236-18-845a-air-charge-temperature-sensor, looks brand new (seems like it and its 2 gen replacement are not available at this time anyway)

As per my last post, I ordered an exact replacement fuel pump. Unfortunately, it seems like the exact replacements (Atkins and Mazdatrix) are not available (maybe a month or two until it is available according to the suppliers).
I did remove the fuel pump today judging, from the gas that l let leak out (about a half-gallon), the gas itself looks clean. So for the immediate I am going to try to "fit" a generic fuel pump.

From what I glean from searching some the posts, the Denso 951-3003 electric fuel pump could work with a minimum of fuss. I'm reluctant to try an eBay used part, the sellers mean well, but you can never be sure. If someone
has a better idea for a substitute it would be appreciated. If necessary, I can always get the exact replacement later when/if it becomes available. Thanks.
don

LongDuck

In my experience, Fuel Pumps (EFI) either work or they don't. If yours is working, it's probably not the problem. Also, while you're pulling out the Fuel Pump, take a very close look at the Fuel Pump cone screen filter on the inlet side. This can become clogged with debris and starve the pump for fuel, cavitating the fuel flow and result in power drop-off at 4k-5k RPM. Also, from the Fuel Pump forward, the next in line is your Fuel Filter. Since you'll likely be removing it to get the Pump out, remove the Filter banjo bolts and LOOK in the inlet side; you should see clear, shiny screen mesh. If you see dirt sediment build up or rust sediment, then the Filter is,catching coming from your Fuel Tank. From there, the next stop is your Fuel Injectors, but if the car runs fine up until the power drops out - your Injectors are probably just fine.

Again, what you're describing sounds like fuel starvation. Take a close look at the Fuel Filters you can get to easily, and then inspect the tank. There's a mesh sock over the fuel pickup inside the tank, but it all has to come out to get to it.

donsz

First, thanks to everyone for their patience on this. I received the new fuel pump yesterday and installed it today. IT LOOKS LIKE IT SOLVED THE PROBLEM! Car revs to top end at all temps, seems to work great.
It has developed something new, it doesn't idle when warm, but I will take look at that later.

FYI: As i mentioned before, I couldn't get an exact replacement fuel pump, everyone I checked was out of stock. What I did do is remove the old fuel pump just to see what could be going on, if anything. I noticed a part number on the
side of the fuel pump: N30413350C, so I googled it. What I found was a Amazon listing:
Description: Fuel Pump Compatible with GSL-SE 12267358 Assembly FD0030,SP1186,2321087601000,MD062978,2321035010,N3 0413350C,12267358,MD074602,MD074182,N304133E8000
URL: It appeared to be almost an exact replacement. So I ordered it ($92). Fits perfect seems to work fine.

It seems like so many things could cause this problem, so thanks for all the inputs.
don