AFM causing no start?

T2Mouse · 04-16-2012, 01:06 AM

Hey guys, i recently purchased a s4 t2 rx7 and the other day while driving the car died on me and wouldn't start again. I traced what i think the problem to be down to the fuel pump not turning on i looked at the factory service manual and have been going through the relays and air flow meter trying to get it to work again. I jumped power straight to the pump and it turned on no problem and i thought that the car should be able to start but it still wouldn't start. I then read that the rx7 fuel pump doesnt come on when the key is turned to on, only when the car is cranked and the afm see's a small amount of air going to it. now because jumping power straight to the pump and having it still not work i feel it must be something else. would a bad afm cause the car to not start at all with the fuel pump jumped on? It is possible that i am with out spark, could someone please tell me how to test for spark?

Raksj04 · 04-16-2012, 10:05 AM

Quote:

Originally Posted by T2Mouse

Hey guys, i recently purchased a s4 t2 rx7 and the other day while driving the car died on me and wouldn't start again. I traced what i think the problem to be down to the fuel pump not turning on i looked at the factory service manual and have been going through the relays and air flow meter trying to get it to work again. I jumped power straight to the pump and it turned on no problem and i thought that the car should be able to start but it still wouldn't start. I then read that the rx7 fuel pump doesnt come on when the key is turned to on, only when the car is cranked and the afm see's a small amount of air going to it. now because jumping power straight to the pump and having it still not work i feel it must be something else. would a bad afm cause the car to not start at all with the fuel pump jumped on? It is possible that i am with out spark, could someone please tell me how to test for spark?

like you do on a lawn mower. pull the EGI fuse and check it. pull it out and put it against the block had a buddy crank it over. if you hold onto the plug you have the potential of getting shocked. check all four spark plugs. If that EGI fuse, under the hood fuse box, is blown you will not get fuel to the engine. You pull it and crank the motor over as part of the deflooding procedure.

88turboii · 04-16-2012, 09:12 PM

AFM will not cause no-start. a bad AFM will cause it to die imediately after it starts.

an easy way to test for spark is pull the boot off the leading coil slightly, and you should see/hear spark arcing. as long as you dont pull it off too far, you wont get shocked lol

another quick way to unflood it is unplug the fuel pump, turn it over like normal at WOT, with all fuses intact. that will guarantee all the extra fuel is burned up in the engine. then plug fuel pump back in, and try to start like normal

you could also pull the CAS sensor and spin it by hand if you want to check for spark/injector firing without wasting battery on the starter. but then you have to know how to reinstall it correctly and re-time it

T2Mouse · 04-16-2012, 10:32 PM

Alright so ive gone through everything i can think of and used the fsm the whole time for basic tests with a multimeter. I determined the fuel pump to be functional and getting power and my fuel pressure gauge reaches 60 psi. i have a walbro if that matters. I also tested for spark and am getting it no problems both coils when a friend cranks the car over. Spark plugs look like they are wet with fuel and im pretty sure i can see some left over fuel being pushed out the open spark plug hole. I know the car is not flooded as i have a functional fuel pump cut off switch that i have always used when it floods and ive gotten it to start every time that way up till now. I looked into the CAS and its resistance is within spec. My timing shouldnt of changed i dont think i was just driving down the road and the engine died and hasnt fired up since.

Raksj04 · 04-16-2012, 10:35 PM

compression check. I would do a compression check. unless you have leaking injectors

T2Mouse · 04-16-2012, 10:53 PM

any way to tell if they are leaking other then flow testing? and tests i can perform with out ripping the intake mani off? I literally just bought this car and had big plans to megasquirt it, so im hoping to god its not a compression problem, i was given receipts for a professional rebuild 20,000 miles ago and alot of other work. seems like if i were to have lost compression it would have been a more dramatic event then just having the motor die suddenly while driving. It was very smooth when the engine died no stumbling or anything just a instant cut out.

here are two pics just to make this thread more interesting for you guys

04-16-2012, 01:06 AM	#1
T2Mouse The Newbie Join Date: Apr 2012 iTrader: (0) Posts: 6 Rep Power: 0	AFM causing no start? Hey guys, i recently purchased a s4 t2 rx7 and the other day while driving the car died on me and wouldn't start again. I traced what i think the problem to be down to the fuel pump not turning on i looked at the factory service manual and have been going through the relays and air flow meter trying to get it to work again. I jumped power straight to the pump and it turned on no problem and i thought that the car should be able to start but it still wouldn't start. I then read that the rx7 fuel pump doesnt come on when the key is turned to on, only when the car is cranked and the afm see's a small amount of air going to it. now because jumping power straight to the pump and having it still not work i feel it must be something else. would a bad afm cause the car to not start at all with the fuel pump jumped on? It is possible that i am with out spark, could someone please tell me how to test for spark?

04-16-2012, 09:12 PM	#3
88turboii destroy, rebuild, repeat Join Date: Feb 2008 Location: Charleston, SC iTrader: (0) Posts: 395 Rep Power: 17	AFM will not cause no-start. a bad AFM will cause it to die imediately after it starts. an easy way to test for spark is pull the boot off the leading coil slightly, and you should see/hear spark arcing. as long as you dont pull it off too far, you wont get shocked lol another quick way to unflood it is unplug the fuel pump, turn it over like normal at WOT, with all fuses intact. that will guarantee all the extra fuel is burned up in the engine. then plug fuel pump back in, and try to start like normal you could also pull the CAS sensor and spin it by hand if you want to check for spark/injector firing without wasting battery on the starter. but then you have to know how to reinstall it correctly and re-time it __________________ 1993 RX-7 Touring MB, stockport 13B-REW, 9.4CR rotors, T04S 60-1/p-trim single turbo 1986 RX-7 Base project track beast

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04-16-2012, 10:32 PM	#4
T2Mouse The Newbie Join Date: Apr 2012 iTrader: (0) Posts: 6 Rep Power: 0	Alright so ive gone through everything i can think of and used the fsm the whole time for basic tests with a multimeter. I determined the fuel pump to be functional and getting power and my fuel pressure gauge reaches 60 psi. i have a walbro if that matters. I also tested for spark and am getting it no problems both coils when a friend cranks the car over. Spark plugs look like they are wet with fuel and im pretty sure i can see some left over fuel being pushed out the open spark plug hole. I know the car is not flooded as i have a functional fuel pump cut off switch that i have always used when it floods and ive gotten it to start every time that way up till now. I looked into the CAS and its resistance is within spec. My timing shouldnt of changed i dont think i was just driving down the road and the engine died and hasnt fired up since.

04-16-2012, 10:35 PM	#5
Raksj04 I have Ultra power in me. Join Date: Sep 2011 iTrader: (2) Posts: 457 Rep Power: 14	compression check. I would do a compression check. unless you have leaking injectors

04-16-2012, 10:53 PM	#6
T2Mouse The Newbie Join Date: Apr 2012 iTrader: (0) Posts: 6 Rep Power: 0	any way to tell if they are leaking other then flow testing? and tests i can perform with out ripping the intake mani off? I literally just bought this car and had big plans to megasquirt it, so im hoping to god its not a compression problem, i was given receipts for a professional rebuild 20,000 miles ago and alot of other work. seems like if i were to have lost compression it would have been a more dramatic event then just having the motor die suddenly while driving. It was very smooth when the engine died no stumbling or anything just a instant cut out. here are two pics just to make this thread more interesting for you guys