Hey guys, lately I've been working on a 1985 RX7. It has an engine that from what I understand has been ported. Unfortunately its just been sitting in front of my house for ages now and it wont start up.
This past week I replaced all of the small vacuum lines and the heater core, they both had leaks. Today I got a new battery and tried to start it up. The engine turned, I could see the belts moving and hear it. It wouldnt start. I tried turning the key 3/4 for a bit and still it wouldnt start. I opened the gas cap and there was some nasty crud in there... After more reading I decided to drain the tank and the fuel was a weird color so I'm assuming it wouldnt be good anymore anyways. I pulled the tank off after draining and thats where we are now.
Hopefully Ill be able to clean the engine and lines of this nasty old fuel/crud. My question is what all do I take out and clean?
Anyways if you have cleaned out the entire fuel system before please share what to remove, where it is, and what to do to clean it.

Ill keep using the search tool and google until someone replies but I have been looking for around an hour now and I cant find much.

 

You'll need to have the injectors cleaned professionally at an injection shop.

Also, flush out the ENTIRE fuel system and replace the associated filters. You'll probably need a new fuel pump as well. Clean the whole tank inside, blow out all the lines, etc.

This should help:
http://www.aaroncake.net/rx-7/unstore.htm

 

How do you get to the injectors? or do i have to take it in? Will the dirty injectors prevent it from running?
that link is awesome! I stumbled upon your website last night and read that exact page. What filters are there other than the fuel filter?
Im sure you can tell, I have no car experience. Ive been google-ing everything and its been going great. Thanks for your help and your website.

 

welcome to the board.

if you have basic metric tools, then just download a copy of the FSM and do it. you'll need to remove the intake manifold - and while somewhat tedious, it's not really difficult. for me, the hardest part is usually removing all of that dried up, stuck-on gasket original material. you can access the injectors, rail and lines when all the intake stuff is out of the way.

dirty injectors won't necessarily prevent it from running. completely clogged injectors will. dealing with either is the same difference - send them to professionals for cleaning/refurbishing or replace them with new.

http://auto.howstuffworks.com/fuel-injection3.htm

 

Good to know. I like to do things on my own for the most part, its a lot cheaper and I get a lot more satisfaction from it. Ive already removed the extension manifold once before. I need to get my hands on a Haynes manual if Im going to do the injectors. Would it be more cost efficient to have them cleaned or buy new ones?

It looks like I should replace the fuel filter, clean the fuel pump (do i need to clean the Fuel Pump?), and maybe replace the charcoal canister. Ill also remove the Fuel Injector... After seeing it in the FSM I recognized it and it should only be a few bolts... if anything it will be difficult to figure out because If I remember right I wasnt able to get the socket to one bolt because it was blocked by fuel line.
When I have the fuel pump and injectors out Ill pull all the hoses and blast them with the compressor...

I noticed a leak on the back differential (I think thats the name for it.) Is this something Ill have to fix? Or is it from sitting over time?

 

Just have them cleaned. The shop that does the work will tell you if they are not salvageable.

You need to clean the entire fuel system. Without question, replace the filter but only after the whole system has been cleaned. With the upper intake off, fuel injector removal is accomplished by taking out the two bolts that hold down the fuel rail. Don't lose the spacer between the rail and the center iron.

 

I broke a vacuum line distributor... actually the only one in the engine bay. Its black and goes from one 4mm vac hose to 4 4mm vac hoses... Do you guys know anywhere I can purchase these? Neither Orielly or this store Merle's had 'em.

Is there any chance there was no spacer? I swear I looked everywhere ahah Im almost positive there was not one because while removing the rail I had my hand where a spacer would be to keep it from falling anywhere. And I looked thoroughly for at least 5 mins... found nothing.

The injectors are being cleaned today. So is the fuel tank... I couldnt work around the baffles so the Pro's can handle it.
I have the whole fuel system opened up and Ive been blowing compressed air through it whenever I get bored... Probably over kill the lines seem empty.

There's a small round filter on the inside of the tank for the main fuel line, whats it called?
There was also a mini-cone filter I found while blowing air through a line... I dont know where it belongs.
Ill purchase a new fuel filter... Is there anything else I can do with these parts off to help the thing start/run better when it starts?

Once everything's back on I plan to drain and replace the oil. Both engine and transmission if its easy enough.... My differential has oil all over the bottom of it how can this be fixed/what is the problem? Im just assuming theres a gasket back there that needs to be replaced.

Sorry for all the questions. Thanks ahead for the answers!

 

welcome. what part of az are you in?

if you just need a vacum tee you you should be able to find universal ones at checker, autozone, or the like.

 

yes i have found some at pepboys before

 

Hey dude I live in Tucson AZ, just off the freeway... good to see there are people around me!

I ended up using three tee's connected to each other to achieve four outputs... the trouble was finding and adapter that goes from one to four hoses.

So today I put the injectors and manifold back on. I changed the oil and I put in a new oil/fuel filter... I need to get a sock filter for inside the tank and possibly a new fuel pump...

Can anyone describe how to test my fuel pump? I tried putting the pump intake in some water and turning the engine over because I thought that would run the pump for a few seconds. Nothing came out of the other end.
I know theres a way to "short" the fuses to make the pump run full time. However, I have no idea how to do this.
Also, does the pump disconnect from the electrical at the pump or in the vehicle? I had trouble trying to remove its two power lines so I gave up and left it hanging...

 

The fuel pump electrical plug is located under the driver's (left) side rear storage box. You need to remove the storage bin to get to it. Under the hood, behind the air box (holds the air filter) are two empty plugs. One is green. The other has a black rubber shroud covering it. If you connect a jumper wire between the 2 terminals in the shrouded plug, the fuel pump should be on whenever the key is on. Never test the fuel pump with water. Use fuel. Here is the FSM procedure for testing the pump.

 

This worked. The beast now runs! getting insured today.

 

The mechanic says he got it to 34ppm HC and .02% CO. Im not sure what that means. The rx7 has a problem, when it heats up it stops running. It can run for 20 minutes possibly longer but at some point it seems to die. The mechanic recommends I drop the fuel tank and replace the lines but Ive done that once before and it sucked. lol. There are also solenoids acting up, he says.

He says he has some ideas and hes confident I can do the work but he pretty much doesnt want to. Ill update again with what he thinks might fix it, if youve experienced a problem like this feel free to chime in.

 

Check and adjust the TPS.

Check the ECT.

 

what is the ECT? how do i test it???

Also, he keeps saying its some sort of vapor lock problem from the heat in our area. Can someone explain what a vapor lock problem is.

 

Vapor lock doesn't exist with fuel injection.

ECT is the Engine Coolant Temp sensor. You will find testing procedures in the FSM I linked to.

 

Alright the TPS has been adjusted.

I have yet to check my ECT, but it will be done soon.

My mechanic says he has been having the same problem with his first gen, due to the heat here. When the vehicle has air moving through the engine bay and is moving nothing goes wrong.
The vehicle gets starved for fuel when hot and when this happens Im able to get it moving enough to park it off the road by feathering the gas pedal. When im cruising down the road it wont shut off, however in drive thru's and at lights or when turning the car on/off the vapor lock happens. Once again it only happens when warm.

He was going to have to charge me to find the problem so instead we are brainstorming and Id like to figure it out on my own to save funds.

He took temperature readings for the shroud that the fuel pump mounts to. He said it was in the high 300* F. The only common denominator between his vehicle and mine are the fuel pumps. We both have an Airtex fuel pump installed. I need ideas for cooling my pump or insulating it to prevent this "overheating."

His other idea was to mount a fan for airflow to the fuel rail in the engine bay, since in the SE's the rail has very little flow. Which could possibly also be causing my problem.

Anyways any ideas on what might be causing these fuel problems would be appreciated. Im going to be dropping the tank and swapping out the old lines soon. Any ideas on how to fix the pumps issues would be appreciated as well.

 

The fuel system has a return line. The fuel is always moving in the lines from the tank, to the pump, through the lines, through the fuel rail and back into the tank. The temperature in one area would need to be a lot more than 300 to instantaneously heat the fast moving fuel enough to turn it into vapor. Like Aaron said its not vapor lock.

I've been through this process at least 5 times (car sitting for years-make it run)
Drop the tank and have it cleaned at a radiator shop or DYI with something like this...
http://www.por15.com/FUEL-TANK-REPAI...ductinfo/FTRK/

You can look into the tank without removing it. Jack up the left rear and remove the wheel. Remove the plastic panel that covers the rear of the wheel well. Remove the 8 small phillips screws and the round plate that holds the fuel level sending unit. It will probably look something like this inside.



I've cleaned several tanks with the Marine Clean degreaser that POR-15 sells. No need to reseal unless the tank is rusted. This tank is not rusted. The varnish formed from the old fuel looks like rust, but after using Marine clean and boiling water the inside looked shiny and new.

Next I would remove the upper intake manifold and remove and clean the injectors. $50 or so. These guys do a good job. http://www.witchhunter.com/ Get new injector o-rings and grommets from Mazda or http://www.mazdatrix.com/

After blowing out the lines with compressed air, installing a new fuel filter and adding a few gallons of fresh fuel I would try to start it. Finally I would use this excellent write up by David Lane to clean and adjust the BAC, TPS etc. http://mrmazda.no-ip.com/gslseidle.html

 

I did all of these things before starting the vehicle for the first time. Its now running with issues when it warms up. Next time I run out of fuel I plan to drop the tank once more and replace all of my fuel lines.

When the vehicle stops running after it warms up it can be started by feathering the gas pedal. The mechanic says also that if you can hold it at 3-4k RPMs by feathering that it could be kept running. I havent been able to do this, it just wants to die out once hot.

Im also going to be mounting fans blowing air across my fuel rail and my fuel pump. This is because fans are cheap and Id like to see if my mechanic's theory about airflow on them works.

Since it isnt vapor locking what do you guys think could be starving the engine of fuel, once it warms up?
Thanks for all the help so far! without you guys id still have a big red brick in my driveway.

 

You didn't say whether you had replaced the fuel pump with new or just cleaned up the old one. Sometimes with hot run issues I've run into the pump being marginal. Another possibility would be the fuel pump relay. Sometimes these can cause intermittent problems when they get hot. Also check all of your electrical connections and wires, especially the ground. They do really weird things when the ground is not good enough. If you have access to a fuel pressure gauge it would be helpful to know what fuel pressure you have when you have the problem. I may be all wet on this because it's hard to diagnose something across the internet. But these are all problems I've run into with various vehicles. I had the same problem with an F700 Ford truck which turned out to be the mother board warping in the Electronic Ignition module, thankfully that shouldn't be your problem with an RX7, much better quality electronics in the Mazda. As the others have said, vapor lock is not an issue with fuel injection. The fuel is under too much pressure to boil, kind of like a pressure cooker raising the boiling point of water. If you don't have pressure when hot, it has to be one of the above things in my experience. You won't know for sure until you can find out what the fuel pressure is doing when it starts cutting out. I hope this helps.

 

Maybe Airtex fuel pumps (never heard for that name) are just crappy pumps?

If you really want to troubleshoot the fuel pump, connect up a fuel pressure gauge and take readings while moving and while stationary.

Surprising the mechanic didn't suggest that.

 

The pump was a good pump, as it turns out. The fuel lines, being so old, were warming up and letting air in. I changed out all the engine bay fuel lines and the fuel pump / filter lines. It used to be really jumpy and didnt accelerate smooth once warmed up. Now everything runs nice, warm or cold.

 

Glad to hear you've got it figured out. It's always the little things that get you.