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Discussion Starter #1
Just picked up this mustang as a project. Wont rev past 3k like its hitting a rev limiter or something.
New iac
New tps
New fuel filter
New map
New coolant temp sensors (both)
New spark plugs (m/c)

This mustang don't have maf.
Its set at 0 degrees timing hits almost 20 when reved up idles great.
30psi of fuel pressure.



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Just picked up this mustang as a project. Wont rev past 3k like its hitting a rev limiter or something.
New iac
New tps
New fuel filter
New map
New coolant temp sensors (both)
New spark plugs (m/c)

This mustang don't have maf.
Its set at 0 degrees timing hits almost 20 when reved up idles great.
30psi of fuel pressure.



Sent from my SM-G960U using Tapatalk
Base timing is where? It should be around 10*. Scan for codes.
 

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30psi is low for fuel pressure. Should be 39 at idle. as 90lxwhite said, base timing should be at 10deg BTDC with spout out. 20 is also very low for total advance when revving it up. I have roughly 29 to 40 deg of total advance depending on load. Not saying yours should be exactly that, but should be ballpark.
779308
 

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Discussion Starter #5
I agree that the fuel pressure is low. Would the fuel pressure regulator be the cause?
I'll reset timing to 10 as the base.

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I agree that the fuel pressure is low. Would the fuel pressure regulator be the cause?
I'll reset timing to 10 as the base.

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Could be a cause. When the pump primes does it hold pressure for a decent amount of time? or does it leak way down quickly?
 
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Discussion Starter #8
I was just sitting here thinking. I suspected a fuel issue and so I did replace the fuel filter. Right after that I did get great respose and I thought I had figured it out. Took it maybe 1/2 mile down the road and it acted up again and won't come back out of it. Could a fuel cap be bad and not allowing the fuel tank to vent? Maybe when I did the fuel filter it allowed the tank to breathe for a min. Mmm

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I was just sitting here thinking. I suspected a fuel issue and so I did replace the fuel filter. Right after that I did get great respose and I thought I had figured it out. Took it maybe 1/2 mile down the road and it acted up again and won't come back out of it. Could a fuel cap be bad and not allowing the fuel tank to vent? Maybe when I did the fuel filter it allowed the tank to breathe for a min. Mmm

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Nah, it’s not going to be the cap. The pump should prime between 35-40 psi. Sometimes it takes two or three primes to get it there if it’s been sitting awhile. This is just a guess but if it’s not hitting the 35-40 psi mark when you prime it I’d suspect the pump is on its way out. If it hits 40 psi and then it leaks down right away look at the regulator.
 

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Discussion Starter #10
Ok so after like 3 cycles of the key I get 40psi non running. And it's staying steady

At idle it drops to 30 and will get up to speed if you slowly hit the gas if you mat the gas pedal it falls on its face ugh
 

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At idle it drops to 30 and will get up to speed if you slowly hit the gas if you mat the gas pedal it falls on its face ugh

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Disconnect the vac hose (cap end with finger) from the regulator when it’s idling. It should jump up to around 40 psi.
 

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Discussion Starter #12
Disconnect the vac hose (cap end with finger) from the regulator when it’s idling. It should jump up to around 40 psi.
Yes it does. Just replaced it regardless. I'm at a loss. It has no power driving down the road. No smoke or noises from the engine. Its something dumb has to be.
 

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Yes it does. Just replaced it regardless. I'm at a loss. It has no power driving down the road. No smoke or noises from the engine. Its something dumb has to be.
The distributor is stabbed in how it’s supposed to be and the timing is all good? Firing order good?
If it’s not a fuel issue, what’s that leave, if ignition?
 

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Discussion Starter #14
The distributor is stabbed in how it’s supposed to be and the timing is all good? Firing order good?
If it’s not a fuel issue, what’s that leave, if ignition?
So to time it i unplug the spout from the dist harness set to 10 then plug the spout back in correct?
 

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Seems a bit odd. I have owned a bunch of these GT's of those years. Of the things you have worked on, i would recheck the Spark Plug Wiring. There are two different firing sequences for 302 Engines. There is one sequence for the early 302's and I believe it was used on the 302 Truck Engines (non-roller cam) which had bank firing injectors. The Fuel Injected Mustangs (roller Camshaft) had a different firing order, same as the 351, if I remember right. Easy to get Spark Plug Wires routed wrong if you don't remove and install them one at a time.

I would also check timing. Yours seems a bit retarded. I advance my timing a bit at a time, until it pings under load slightly, then retard it slightly and then check it with a timing light to see if it is where I want it. If anyone pulls the distributor, they can be a bear to get installed correctly. You did not say anything about the Distributor so I will not go into that.

Mustang Fuel Injection is pretty simply and generally reliable. Post any further troubleshooting.

Seems a bit odd. I have owned a bunch of these GT's of those years. Of the things you have worked on, i would recheck the Spark Plug Wiring. There are two different firing sequences for 302 Engines. There is one sequence for the early 302's and I believe it was used on the 302 Truck Engines (non-roller cam) which had bank firing injectors. The Fuel Injected Mustangs (roller Camshaft) had a different firing order, same as the 351, if I remember right. Easy to get Spark Plug Wires routed wrong if you don't remove and install them one at a time.

I would also check timing. Yours seems a bit retarded. I advance my timing a bit at a time, until it pings under load slightly, then retard it slightly and then check it with a timing light to see if it is where I want it. If anyone pulls the distributor, they can be a bear to get installed correctly. You did not say anything about the Distributor so I will not go into that.

Mustang Fuel Injection is pretty simply and generally reliable. Post any further troubleshooting.
Fuel Pressure seems about right for having it under vacuum. Probably OK.
 

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Fuel pressure specs show 35-45 with KOEO (no vacuum to pressure regulator). Your ign. timing seems retarded; should be 10 BTDC base timing and when you rev it up to 2500, should definitely be more than 20, usually close to 30 BTDC.
 

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Discussion Starter #20
When I key on fuel pressure don't move. I have to cycle the key like 4 times to get it to 40psi. I would think key on it should build without having to cycle the key correct?
 
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