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

Weird starting problem

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Old May 14, 2005 | 08:41 AM
  #1  
fcrotornut's Avatar
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From: texas
Weird starting problem

Well, the altenator, plugs and plug wires are new, the starter is fine.

its like my engien isnt catchign at first, i have to listen carefully for it to catch, when it does, i have to give it gas to keep it from dying.....

this is all on a gsl-se

any idea what it could be?
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Old May 14, 2005 | 09:11 AM
  #2  
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You figure it out tell me as well, it's the same problem I'm having.

- Tech
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Old May 14, 2005 | 10:13 AM
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From LongDuck

Actually, it sounds to me like it's a problem with the hot-start assist system, which is the EFI ability to take in measurements of intake air temp sensors (2; 1 at the AFM, 1 at the DEI chamber), and from the differential, the ECU decides to lean the mixture to help with hot-start. If either of these sensors are not functioning correctly, they may not be triggering the hot-start assist loop in the ECU, and you'd get an overly rich mixture, possibly leading to flooding, as you've described.

The other sensor that I would check is the coolant temp sensor at the back of the water pump. This sensor is also used by the ECU to determine whether the engine is warm. It is usually tied into when the ECU turns off the 'choke' or cold-start cycle, but other posters here have had problems with low fuel mileage, flooding on startup, and popping/backfiring from a coolant temp sensor that's returning a 'cold' signal all the time (disconnected makes the engine think it's cold).

Have a look at your wiring harness to these sensors and see if it may be an intermittent short. Also, check the plastic plug (green) going to the WP coolant temp sensor - sometimes these crack with age and the plug will come loose or unlatched, thereby returning a 'cold' condition to the ECU.

Let us know what you find; there may be more to troubleshoot to assist,

FYI - standard 'start' cycle for an EFI SE is 1) pedal to floor and then off COMPLETELY, 2) turn key to 'start', 3) crank until engine fires. If you hold the pedal to the floor, the ECU is going to attempt to add fuel once the engine catches, which may induce flooding. The 'Fast Idle Cam' gets reset when you push the pedal down prior to start - that's all the TB airflow you need, otherwise you risk flooding. The car is smart enough to take care of that for you...


And from RX7Doctor

I probably have covered this a billion times,lol.
The 2 most inherent things on the Se for what you are describing is.
1). The injectors are leaking, Which means instead of fuel returning via the return line after the hold pressure has bleed down, it goes thru the injectors into the rotors.
How to verify. After parking the vehicle, let it sit for a couple minutes. Then remove the pressure fuel hose by wrapping a rag around it so you do not get sprayed with fuel. This will release all the pressure in the line. Then reconnect and start next morning. If problem is gone than either need to have injectors cleaned or use a product that we have here called Bg's 44k.
2). And i should of posted this first because this is the easiest to verify. Turn the key to the on posistion but do not start and listen for the fuel pump. If it is on before you start to crank then the AFM is bad and putting fuel into the injectors before it should. Cure, replace AFM.
If it turns out not to be one of the above let me know and will go into the dark abyss of diagnostics with you.
__________________
RX7DOCTOR


try those, they worked for me.

Steve
1984 GSL-SE
1986 Jag
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Old May 14, 2005 | 11:21 AM
  #4  
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Yeah, what he said.

(marking the thread for a return later...)
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Old May 15, 2005 | 02:32 AM
  #5  
fcrotornut's Avatar
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From: texas
ok, after a compression test and searching.


leaky injectors.

sucks, but could be worse, the first suspect was bad compression or a seal.

but when i pulled the plugs and did the ghetto compression test, all the swoosh sounds im supposed to listen for were there, and strong.

well, also in doing so i managed to get some of that excess fuel out and she cranked right over, no problem at all.

so im thinking its the injectors, ill see in the morning how it starts, i figure overnight they will have had plenty of time to leak again.
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