1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

gsl se hesitating

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Old 07-22-10, 10:42 PM
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gsl se hesitating

well i bout a gslse that wasn't running the previous owner said it just wouldn't start one day and its been park ever since. well i took it home and unhooked the fuel lines and it wasn't getting any fuel so i replaced the pump and filter.. after all that it ran good . i drove it to the gas station and put gas and took a long drive it drove amazing.. well the next day i decided to take it to work and it took a crap and left me stranded... well when i got home i unhooked the fuel lines again and the fuel was a nasty brown color... so i dropped the tank and cleaned it out. it was pretty nasty.. so i put every thing together and it started and was acting normal so i took it for a drive and i soon as i got on the road it starts hesitating again... well i got back on my drive way was reving it up to around 4000rpms hoping it would clear out wrong.. so i notice it was smoking a little from under the car so i took a look and the cat. was glowing red.. could this be my problem.... ive also change the plugs, wires,cap and button.. so if you guys can help i would appreciate it thanks
Old 07-22-10, 11:48 PM
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if the fuel from the tank was brown and cruddy, i suggest dropping the tank and having it professionally cleaned. you are probably picking up sludgy/tarry gas and sediment. this will ruin/clog the fuel pump the filter, and the injectors. a red hot can can be from running lean, meaning that things are starting to plug up... i have a writeup with pics on the fuel tank removal if you need it.
Old 07-22-10, 11:57 PM
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Originally Posted by mazdaverx713b
if the fuel from the tank was brown and cruddy, i suggest dropping the tank and having it professionally cleaned. you are probably picking up sludgy/tarry gas and sediment. this will ruin/clog the fuel pump the filter, and the injectors. a red hot can can be from running lean, meaning that things are starting to plug up... i have a writeup with pics on the fuel tank removal if you need it.
well i cleaned it pretty good. i unhooked the fuel line before i started it to make sure all the old gas was out of the line...i let the pump run until the fuel was clean..i was kind of thinking maybe sending off the injectors next...
Old 07-23-10, 12:23 AM
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yea, but if the car sat with gas in teh tank, there's probably old varnished gas in there and the new gas is probably loosening it up and its getting past teh pickup screen and into your fuel system.

best place i've found for cleaning injectors is www.witchhunter.com. outstanding service and a 3 or 4 day turnaround. you ship them the injectors on monday and you'll have them by thursday or friday.
Old 07-23-10, 12:49 AM
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I would recommend performing a fuel volume test first to see what the delivery is up front.
TPS out of adjustment will cause hesitation as well as only firing on one injector.

Check the FSM for the test procedures for the above mentioned.
Old 07-23-10, 12:56 AM
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Originally Posted by Rx-7Doctor
I would recommend performing a fuel volume test first to see what the delivery is up front.
TPS out of adjustment will cause hesitation as well as only firing on one injector.

Check the FSM for the test procedures for the above mentioned.
well i pulled the plugs and t1 and l1 were ok looking but when i pulled the rear plugs they were sord of white.... is there a right up on a fuel volume test..
Old 07-23-10, 01:24 AM
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Check the FSM for the test procedures for the above mentioned. __________________
RX-7Doctor




Originally Posted by madazfiend/1
well i pulled the plugs and t1 and l1 were ok looking but when i pulled the rear plugs they were sord of white.... is there a right up on a fuel volume test..
Old 07-23-10, 05:32 AM
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Originally Posted by madazfiend/1
well i pulled the plugs and t1 and l1 were ok looking but when i pulled the rear plugs they were sord of white.... is there a right up on a fuel volume test..
White plugs means lean, as does the glowing cat/exhaust (or clogging from internal failure) I would look into fuel flow, but also injectors. If one bank is running fine, and the other isnt, I would suspect the injectors for that bank. Get those done. If you have access to it, a noid light set will tell you if the injectors are firing.

Just start at one end and work your way to the other. Tank cleaned out, pump/filter clean and new (keep tossing new filters on it for a while), lines cleaned out up to the firewall, injectors cleaned (flush the rail while theyre out), and give that all a shot.

Keep an eye on that cat also. If its not failing now, heat like that isnt great for them. It can burn them up and cause them to fall apart inside and cause a restriction and loss of power.

~T.J.
Old 07-23-10, 10:47 AM
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well thanks guys i will check the injectors and the fuel volume... ill post the results. thanks Joel
Old 07-23-10, 01:50 PM
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There are only "2" injectors on a SE engine. 86 on up had 4 injectors.

"Heat" is not the killer of catalytic converters, Too much unburned fuel or burning oil is what deteriorates the internals of the converter.

Separate the system from where the down pipe from the exhaust manifold meets the front catalytic converters and from where the rear catalytic converter meets the connecting pipe that goes to the muffler. Get some PB blaster and spray down all the nuts including the heat shielding as they tend to rust and seize over years. Once you get the system off you can inspect the internals. Buy new exhaust gaskets before you take down the system as more than likely they will be in poor shape. Do not buy ones that are generic! Get the correct ones from a discount Mazda Dealer like Mazdaautoparts.com.

It take a tremendous amount of gunk to get past the fuel filter on a SE unlike a Carburetor model. Also inside of the SE fuel hose their is a Screen that can easily get restricted if you had issues inside of the tank.

Before you pull the intake manifold and decide to send the injectors out for cleaning you can test to see if you are getting the proper inputs (grounds and such) to the ECU. Sometimes one of the wires at a injector will get corroded or loose from the deterioration of the plastic wiring housing that attaches to the injector.

If you decide to send out the injectors anyways which I always do when I buy a SE model then you can test to see if the injectors are spraying by running a jumper wire to the Green 2 pin connector near the AFM. Once you pull the injectors out you then take some Nyties and secure them to the fuel rail. If you don't they will pop out of the fuel rail as soon as you energize the fuel pump. Put a small glass or suitable container under each one when performing this test. If you do not have fuel coming out of one injector then you more than likely have a fusible link or corroded connector or broken wire. If when separating the injector wiring housing from the injectors that they fall apart (they get brittle from age and heat) then buy replacement ones. They are available from Napa and I have the part number if you need it.

You will also want to replace the 2 rubber fuel lines under the intake that are the supply and return hoses for the fuel system. One will be high pressure and the other low. Just get enough Fuel injection hose for both. I recommend taking pictures of the Vacuum hoses that go to the intake pieces or making notes on paper as the first time you do this it can be confusing. Also there is a vacuum Spider (connecting) block where all the 4 hoses join that is under the intake manifold. Inspect it for cracked hoses and or cracked plastic at the spider.

Some things to replace while you have at minimum the upper intake and plenum off.

1- Coolant supply hose that runs from the back of the water pump housing to the thermal valve at the throttle body. (Recommend you separate the T/body from the plenum before you pull the plenum as it is easier to to undo the hose at the T/body. Otherwise you need to undo it at the water pump housing in order to get the T/body/plenum off. Also replace the coolant hose that goes from the rear iron of the engine to the thermal valve. Another preventative maintenance item is the Coolant Temperature Sensor at the back of the water pump housing. It is a failure item that will cause the SE engine to run very rich. Also be careful when removing the plastic connector as it may be very brittle and crack when separating it from the sensor.

If you do go the route of removing the upper intake to send the injectors out then I suggest you go one step further and remove the lower intake. That way you can clean the 5th / 6th port actuator sleeves. This is another area on the SE that can have issues over time due to the amount of crude that gets in there. Before you start your disassemble process if you are sending the injectors out. Start the engine and get under the hood. Go to the passenger side and rev the engine up and see if the rods at the actuators start to move. If they do not then either they need to be cleaned or the hose that is used for back pressure from the exhaust system is cracked or missing.

If you going to do all of the above work which I highly recommend then order all of your parts in advance. If you send the injectors out then WitchHunters will supply new injector seals. He normally supplies the small O-ring at the bottom and the seal at the top but do not remember if he supplies the large injector grommet at the base where it goes into the air bleed nozzle where the injector sprays the fuel. Check with him so that you know whether you need to purchase those from another site.


You will need the following if you do all the above listed work.

The 2 coolant hoses that go to the throttle body.
Upper and lower intake manifold gaskets. (Don't need the one that is between the plenum and upper manifold because you do not need to separate and I have never had a bad one).

2- 6 port actuator gaskets.
1- ACV gasket if you want to be really proactive because that gasket if it fails causes all kinds of issues.
3-Coolant temperature sensor for the ECU.
Approx 1ft to 1 1/2 Ft of fuel injection hose.
Coolant- Also determine if you want to replace the Engine Thermostat at this time as preventive maintenance since you are going to be losing coolant from the hose replacement.
Exhaust manifold gasket to engine- Again this is just a preventive maintenance item and is very easy to replace if you are doing all the other work.


Parts that may need replacement-

Injector wiring housing at the injector.
Coolant level sensor wiring housing at the Sensor.
Vacuum Spider under intake manifold.
Vacuum chamber under intake manifold near left side of engine. Has one vacuum hose that attaches to it.


Remember the FSM is your friend when needing to reference for test and or replacement parts assistance. :-)

Last edited by Rx-7Doctor; 07-23-10 at 01:53 PM.
Old 07-23-10, 05:46 PM
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Originally Posted by Rx-7Doctor
There are only "2" injectors on a SE engine. 86 on up had 4 injectors.

"Heat" is not the killer of catalytic converters, Too much unburned fuel or burning oil is what deteriorates the internals of the converter.

Separate the system from where the down pipe from the exhaust manifold meets the front catalytic converters and from where the rear catalytic converter meets the connecting pipe that goes to the muffler. Get some PB blaster and spray down all the nuts including the heat shielding as they tend to rust and seize over years. Once you get the system off you can inspect the internals. Buy new exhaust gaskets before you take down the system as more than likely they will be in poor shape. Do not buy ones that are generic! Get the correct ones from a discount Mazda Dealer like Mazdaautoparts.com.

It take a tremendous amount of gunk to get past the fuel filter on a SE unlike a Carburetor model. Also inside of the SE fuel hose their is a Screen that can easily get restricted if you had issues inside of the tank.

Before you pull the intake manifold and decide to send the injectors out for cleaning you can test to see if you are getting the proper inputs (grounds and such) to the ECU. Sometimes one of the wires at a injector will get corroded or loose from the deterioration of the plastic wiring housing that attaches to the injector.

If you decide to send out the injectors anyways which I always do when I buy a SE model then you can test to see if the injectors are spraying by running a jumper wire to the Green 2 pin connector near the AFM. Once you pull the injectors out you then take some Nyties and secure them to the fuel rail. If you don't they will pop out of the fuel rail as soon as you energize the fuel pump. Put a small glass or suitable container under each one when performing this test. If you do not have fuel coming out of one injector then you more than likely have a fusible link or corroded connector or broken wire. If when separating the injector wiring housing from the injectors that they fall apart (they get brittle from age and heat) then buy replacement ones. They are available from Napa and I have the part number if you need it.

You will also want to replace the 2 rubber fuel lines under the intake that are the supply and return hoses for the fuel system. One will be high pressure and the other low. Just get enough Fuel injection hose for both. I recommend taking pictures of the Vacuum hoses that go to the intake pieces or making notes on paper as the first time you do this it can be confusing. Also there is a vacuum Spider (connecting) block where all the 4 hoses join that is under the intake manifold. Inspect it for cracked hoses and or cracked plastic at the spider.

Some things to replace while you have at minimum the upper intake and plenum off.

1- Coolant supply hose that runs from the back of the water pump housing to the thermal valve at the throttle body. (Recommend you separate the T/body from the plenum before you pull the plenum as it is easier to to undo the hose at the T/body. Otherwise you need to undo it at the water pump housing in order to get the T/body/plenum off. Also replace the coolant hose that goes from the rear iron of the engine to the thermal valve. Another preventative maintenance item is the Coolant Temperature Sensor at the back of the water pump housing. It is a failure item that will cause the SE engine to run very rich. Also be careful when removing the plastic connector as it may be very brittle and crack when separating it from the sensor.

If you do go the route of removing the upper intake to send the injectors out then I suggest you go one step further and remove the lower intake. That way you can clean the 5th / 6th port actuator sleeves. This is another area on the SE that can have issues over time due to the amount of crude that gets in there. Before you start your disassemble process if you are sending the injectors out. Start the engine and get under the hood. Go to the passenger side and rev the engine up and see if the rods at the actuators start to move. If they do not then either they need to be cleaned or the hose that is used for back pressure from the exhaust system is cracked or missing.

If you going to do all of the above work which I highly recommend then order all of your parts in advance. If you send the injectors out then WitchHunters will supply new injector seals. He normally supplies the small O-ring at the bottom and the seal at the top but do not remember if he supplies the large injector grommet at the base where it goes into the air bleed nozzle where the injector sprays the fuel. Check with him so that you know whether you need to purchase those from another site.


You will need the following if you do all the above listed work.

The 2 coolant hoses that go to the throttle body.
Upper and lower intake manifold gaskets. (Don't need the one that is between the plenum and upper manifold because you do not need to separate and I have never had a bad one).

2- 6 port actuator gaskets.
1- ACV gasket if you want to be really proactive because that gasket if it fails causes all kinds of issues.
3-Coolant temperature sensor for the ECU.
Approx 1ft to 1 1/2 Ft of fuel injection hose.
Coolant- Also determine if you want to replace the Engine Thermostat at this time as preventive maintenance since you are going to be losing coolant from the hose replacement.
Exhaust manifold gasket to engine- Again this is just a preventive maintenance item and is very easy to replace if you are doing all the other work.


Parts that may need replacement-

Injector wiring housing at the injector.
Coolant level sensor wiring housing at the Sensor.
Vacuum Spider under intake manifold.
Vacuum chamber under intake manifold near left side of engine. Has one vacuum hose that attaches to it.


Remember the FSM is your friend when needing to reference for test and or replacement parts assistance. :-)



dam they dont call u the doc for nothing... great info thank a lot i have all weekend to perform surgery..... i really appreciate all the help guys.. Joel
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