Fuel System Question...
03-18-04, 09:16 PM
#1
Fuel System Question...
I just bought an '87 TII two week ago for parts. Its in good shape but has engine issues. I got it to run but its rough! The primary injector on the front housing is leaking real bad. I was wondering why smoke was coming out from under the hood... 
fuel was hitting the exhaust...When i took the UIM off and the primary rail, I accidentally knocked the cap off the pulsation dampener and the screw fell out...but gas wasn't coming out of there. I saw that it was coming out of the injector adn not anywhere else. Whats with that? Was it just its time?
Another Q: I noticed there is a T fitting between the fuel line going to the rails and back to the tank. Its on the driver side of the motor, by the oil filter. Is that factory? It looks custom...whats with it?
Another Q: how does the fuel pump know when to cut on to maintain pressure in the rails? Is there a pressure sensor on the pump...?
Sorry, for the long post.
Thanks,
Ryan
fuel was hitting the exhaust...When i took the UIM off and the primary rail, I accidentally knocked the cap off the pulsation dampener and the screw fell out...but gas wasn't coming out of there. I saw that it was coming out of the injector adn not anywhere else. Whats with that? Was it just its time? Another Q: I noticed there is a T fitting between the fuel line going to the rails and back to the tank. Its on the driver side of the motor, by the oil filter. Is that factory? It looks custom...whats with it?
Another Q: how does the fuel pump know when to cut on to maintain pressure in the rails? Is there a pressure sensor on the pump...?
Sorry, for the long post.
Thanks,
Ryan
03-26-04, 09:48 AM
#2
Queer
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Q1. Injectors?
A1. Injectors will leak sometimes. Just have the rebuilt or cleaned.
Q2. T-Fitting?
A2. This was someones band-aid to stop the car from flooding, most likely because of the fact the injectors were leaking.
Q3. Fuel pressure?
A3. Not sure. The voltage is varied to the pump which will create different pressures. Maybe this is the only way it does it for stock cars. It probably just keeps the pressure high enough and I bet it fluctuates when you are driving. I don't know because I have never had a fuel pressure gauge.
A1. Injectors will leak sometimes. Just have the rebuilt or cleaned.
Q2. T-Fitting?
A2. This was someones band-aid to stop the car from flooding, most likely because of the fact the injectors were leaking.
Q3. Fuel pressure?
A3. Not sure. The voltage is varied to the pump which will create different pressures. Maybe this is the only way it does it for stock cars. It probably just keeps the pressure high enough and I bet it fluctuates when you are driving. I don't know because I have never had a fuel pressure gauge.
03-26-04, 09:58 AM
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03-26-04, 10:56 AM
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****Another Q: how does the fuel pump know when to cut on to maintain pressure in the rails? Is there a pressure sensor on the pump...?****
The fuel pump, pumps when:
1. Anytime the key is HELD to START.
2. Anytime the key is released from START and returned to ON, AND the engine is running. There's a switch in the air flow meter that *makes* when the vane in the afm is pulled aft by the airflow. That switch puts a ground on the Circuit Opening Relay and *makes* the circuit to the fuel pump so it will run.
3. The pump also runs when the key is to ON and the fuel pump check connector has a jumper in it.
As you can see, there is no pressure switch involved.
Search MazdaTrix web site and you'll see what that T-fitting b/t the fuel rails is all about. It bleeds off the fuel rail pressure after you shut the engine down. Normally the rail maintains fuel pressure long after you shut down.
The pulsation damper and the screw: If the thing is not leaking, buy some locktite. Put the locktite on the threads. Gently screw the screw into the damper until you hit resistance. Stop there. Put the cover back on. YOu DO NOT WANT TO USE TORQUE ON THIS SCREW. It screws into a rubber diaphram. If you bottom out the screw and use a twisting motion, you will be twisting the diaphram and it will break and then the thing WILL leak fuel. I've posted pictures of the breakdown of the pulsation damper in the past. So search: Pulsation damper and HAILERS. Mybe you'll find it, maybe not.
The fuel pump, pumps when:
1. Anytime the key is HELD to START.
2. Anytime the key is released from START and returned to ON, AND the engine is running. There's a switch in the air flow meter that *makes* when the vane in the afm is pulled aft by the airflow. That switch puts a ground on the Circuit Opening Relay and *makes* the circuit to the fuel pump so it will run.
3. The pump also runs when the key is to ON and the fuel pump check connector has a jumper in it.
As you can see, there is no pressure switch involved.
Search MazdaTrix web site and you'll see what that T-fitting b/t the fuel rails is all about. It bleeds off the fuel rail pressure after you shut the engine down. Normally the rail maintains fuel pressure long after you shut down.
The pulsation damper and the screw: If the thing is not leaking, buy some locktite. Put the locktite on the threads. Gently screw the screw into the damper until you hit resistance. Stop there. Put the cover back on. YOu DO NOT WANT TO USE TORQUE ON THIS SCREW. It screws into a rubber diaphram. If you bottom out the screw and use a twisting motion, you will be twisting the diaphram and it will break and then the thing WILL leak fuel. I've posted pictures of the breakdown of the pulsation damper in the past. So search: Pulsation damper and HAILERS. Mybe you'll find it, maybe not.
Last edited by HAILERS; 03-26-04 at 11:01 AM.
03-26-04, 11:03 AM
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