1986, fuel pressure regulator - vacuum connection
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1986, fuel pressure regulator - vacuum connection
My 86 seems to run fine while I am driving it. The problem is at idle is wants to surge 400 - 700 rpm. The fuel pressure is 38-39 psi at the valve, but it drops about 8 lb in 1 min. and about another 4 after 2 min. with the engine off. I have read other threads that say check the injectors if this happens, but all have been cleaned and tested a Cruzin Performance and were all fine - he even cleaned the 9th injector. I can't fine in the FSM anything about the vacuum connection on the regulator. how do you test it? With the engine off, it won't hold any pressure using a hand vacuum pump. I have tested the EGR system and it seems OK and no vacuum leaks. Is the regulator vacuum causing the problem.
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My 86 seems to run fine while I am driving it. The problem is at idle is wants to surge 400 - 700 rpm. The fuel pressure is 38-39 psi at the valve, but it drops about 8 lb in 1 min. and about another 4 after 2 min. with the engine off. I have read other threads that say check the injectors if this happens, but all have been cleaned and tested a Cruzin Performance and were all fine - he even cleaned the 9th injector. I can't fine in the FSM anything about the vacuum connection on the regulator. how do you test it? With the engine off, it won't hold any pressure using a hand vacuum pump. I have tested the EGR system and it seems OK and no vacuum leaks. Is the regulator vacuum causing the problem.
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Thanks for your help. I will change the regulator. Does anyone know what the vacuum does to the fuel pressure regulator - increase vacuum will increase fuel available to the rail?
#5
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"it drops about 8 lb in 1 min. and about another 4 after 2 min. with the engine off."
Or the non-return valve on the pump is worn allowing pressure to bleed off on supply side.
When you have the idle surge , does indicated fuel presure change also?
High vac (idle) closes reg reducing fuel ; low vac (accel ) opens reg increasing fuel.
Or the non-return valve on the pump is worn allowing pressure to bleed off on supply side.
When you have the idle surge , does indicated fuel presure change also?
High vac (idle) closes reg reducing fuel ; low vac (accel ) opens reg increasing fuel.
#6
Melting Slicks
Attach your press gauge with the vac tube attached and the eng at idle. Remove the tube. The press should rise.