Hello everyone! Just bought my first rotary, a 94 FD. I am trying to get it running for the first time in more than a year. All fluids have been replaced along with plugs, belts, battery, air filter, fuel filter, fuel pump & sock, and cleaned the fuel tank.

The fuel pump turns on but I still need to find a way to check the fuel pressure.

My main question here is do the compression test results in my link look acceptable? The numbers look great for a cold engine (oil squirted in the plug holes) at roughly 100psi with the schrader valve removed and 125psi total with schrader installed. I am just unsure that all rotor faces are compressing.

https://www.youtube.com/channel/UCQjZkjOloLQu8xBK4iJGbDA

The spark test is also shown there, which looks good. Small blue spark on the lower plugs and a bit bigger, whiter spark in the upper plugs.

Thanks in advance to any responses!

 

great compression..no worries there.

 

Turns out I have extremely low fuel pressure!

Video of the test is shown here:
https://www.youtube.com/watch?v=QBvN...ature=youtu.be

Only 10 psi fuel pressure. It has a brand new fuel filter, new replacement fuel pump (Autobest F4120), and new fuel sock. The tank has been cleaned and there are 10 gallons of fuel in the tank.

Any guesses as to why the fuel pressure would be so low? Maybe the fuel pump o-ring connection is not good enough? I believe that all other connections are good.

 

I checked the fuel pressure directly above the fuel pump on the main line, and it also was only 10psi.

Wondering if it was a low voltage problem, I disconnected the main white (orange interior) plug above the fuel pump, used a jumper wire to "run the fuel pump" and the voltage was 12.0v. Since the battery is at 12.3 volts, I am happy with this.

To give the ground wire the best opportunity possible, I sanded down the fuel pump lid around the ground, and used dialectic grease on the threads before tightening the nut very tight.

Tomorrow I can pull the fuel pump out and check the voltage at the posts. I guess that it too is possible that the pump is not sealing to the output tube since it was tricky to stuff in place initially.

Any thoughts?

Thanks!

 

is that a compression tester that you are using for a fuel pressure tester?

 

Two different testers, don't worry!

Good news: The low pressure was fixed by replacing the rusty terminals on the fuel pump

The bad: It is still not starting. There seems to be a fuel pressure leak somewhere under the intake manifold. The video attached here shows everything in great detail.

https://www.youtube.com/watch?v=k6ae...ature=youtu.be

52psi while starting (before pressure regulator) and pressure drops afterwards, meaning there is a leak which can actually be heard under the manifold like I mentioned. It is not within the fuel line because a max pressure test was done and it held at 80psi (1xx pressure was reached).

So now I need to find out how to access the pressure regulator and other components to check for leaks.

 

If your FPD is original, you may want to replace it (which may or may not be the culprit)

https://www.rx7club.com/2nd-gen-arch...ms-read-60160/

 

Thanks for the response! As far as I know, my FDP is original. I went ahead and took off the air intake to see that it is still buried far below which stinks.

As for finding the problem, I plugged the return fuel lines separately. Plugging one of the return lines did nothing as the pressure dropped quickly.

Plugging the most bottom right line, however acted like I plugged the main fuel line. The pressure shot up high and there wasn't rapid pressure loss. This line I believe is the main fuel return line since it continuously poured out fuel after I opened it even though the fuel line system did not have pressure.

Sooo I believe this means I have a leak somewhere in the fuel return line going back to the tank! If the leak was around the fuel rail at the fpr or fpd, then it should not have held pressure on this test.

Any comments or thoughts are more than welcome Thanks!

 

My thoughts on low fuel pressure are either bad fuel pump, clogged filter, leak, or bad fuel pressure control system (or any combination). If it's a leak, you should be able to smell it. Attached is an outline of the pressure control system (from the '93 service highlights). Could be the solenoid valve (the valve or the vacuum hose), relay, or pressure regulator (supposedly these don't usually fail tho). If you dig down to any of the components under the UIM, you really should replace or delete the FPD.

 

Thanks TomU! Good fuel pump, filter, and no gas smell as far as I know.

Since the fpr should only let fuel through with vacuum like at idle, I feel like this is the problem. If the fpr was closed like it should be, the pressure would not have dropped quickly. If it were the injectors, they would have leaked during the plugged test.

I don't believe the FPD would do anything to this situation if it were bad but good point that I should replace it for safety.

Any other comments are greatly appreciated, you guys are awesome thanks!

 

Took the FPR off yesterday. Put it up to an air compressor and air blows straight through even and low pressure! With no vacuum it should be sealed shut so it looks like we found a problem, and hopefully it is the final problem! Will install a replacement tomorrow.

 

Great news about fuel pressure! However it still does not start or even try coughing.

After changing out the FPR, the pressure goes up to 39psi and holds the pressure as well (drops 1 psi every 1-2 minutes).

I will check tonight to see if it became flooded while trying to start it 4 times (5 second intervals of key turn starting).

Again, the engine cranks great, great compression and spark as of a week ago seen in my youtube video link, and now we have fuel pressure at the rail.

I just learned from the previous owner that the intake air thermo sensor is bad but I think it should still atleast start.

Possible problems I should check that are not letting it start? Here are some I can think of
1. Flooded engine
2. Injectors stuck closed
3. Bad timing? I assumed the position on the eccentric shaft was fine when I bought it.

 

Good to hear you got the fuel pressure sorted. If you're down at the rail level, you should send your injectors out for cleaning. If you've got spark and compression, that only leaves fuel. Having fuel pressure doesn't mean it's getting in the engine, but it does narrow down the variables.

Have you checked your plugs for flooding. If they are gas logged, you could have timing issues, but I think that's somewhat unlikely.

 

Thanks!

Today I sprayed a bit of starting fluid in the intake manifold extension and it started for a brief second, check it out here!
Notice that in the video, the fuel pressure drops a bit when the starter turns on. This makes me think that the injectors open up at first??

The plugs were not flooded as I replaced them again today.

It seems clear to me that the fuel is not getting to the engine since it never even coughs under its own fuel. Now it is time to find a good way to test the injectors! If they do come out then good point, I should send them out for cleaning. I want to drive thoughhhhhh

 

The FSM details how to check the injectors. Personally, I wouldn't mess with it. A shop like RC Engineering will check them, clean them, and provide new O-rings. Turn around is only a week or two. You should also inspect your air bleed diffusers (and replace their O-rings and insulators). You may also want to replace all your rubber from the firewall forward if it's original equipment to include the connection from the primary to secondary rail. Do you want to rely on 20+ yr rubber holding fuel under pressure?

I hear you on getting back on the street. I've been down 2-1/2 years.

 

A week or two would be sweet! Tonight I will check to hear if they are clicking and check voltage from the ecu. If those are both good then I believe that I will need to pull the injectors and send them out. So sorry about 2.5 years man!!!! That is a long time.

 

There was voltage at the X-05 connector and I went a step further by testing at the primary fuel injector plugs. As seen in this video, the rear noid light looks great, the front noid light seems dim, but the fuel injectors are not opening. There is 39 psi fuel pressure at the rail so they should function well.


Time to send the injectors off for cleaning!