Anonymous
Unregistered
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My '91 Trooper with the F.I. 2.6 has recently started idleing slowly and roughly. Once or twice, I have smelled fuel under the hood, although I couldn't find any obvious leaks.
When I pull a vacuum line to the manifold (allowing unmetered air into the manifold), the idle speed increases, suggesting an over-rich condition at idle. I am suspect a bad fuel pressure regulator, which may be allowing too much pressure to the injectors.
Anybody know what the correct fuel pressure should be at idle? Other suggestions on how to troubleshoot this problem?
Thanks,
Dave
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Richard Saylor
Roll Me Over
Reged: 08/02/02
Posts: 3007
Loc: Lockhart, TX
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If idle gets better when you pull a vacuum line, I would check your air filter. You might not be getting enough air into the engine. Fuel pressure for I-TEC engines, with vacuum hose removed from pressure regulator - 42 psi, with vacuum hose attached to pressure regulator - 35 psi.
Richard
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Had an 89 Isuzu Pickup
Had a 94 Mitsubishi Eclipse
84 Honda XL185S
Had an 89 Isuzu Trooper w/ 3.4 V6
01 Toyota Tundra SR5 V8 4Door Access Cab
http://community.webshots.com/user/rsayloriii
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Anonymous
Unregistered
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Thanks Richard, I will check my filter and the fuel pressure. Should I check the pressure between the regulator and the fuel rail, or before the regulator?
Thanks again,
Dave
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Richard Saylor
Roll Me Over
Reged: 08/02/02
Posts: 3007
Loc: Lockhart, TX
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Here's how to check the pressure:
Relieve the fuel pressure, disconnect the fuel outlet hose from the fuel pressure regulator, connect a fuel pressure guage to the outlet hose, start the engine, detach the vacuum hose from the pressure regulator, with engine idling check fuel pressure.
Richard
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Had an 89 Isuzu Pickup
Had a 94 Mitsubishi Eclipse
84 Honda XL185S
Had an 89 Isuzu Trooper w/ 3.4 V6
01 Toyota Tundra SR5 V8 4Door Access Cab
http://community.webshots.com/user/rsayloriii
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Anonymous
Unregistered
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Thanks Richard, I assume you mean attach the fuel pressure guage with a "T" fitting so fuel continues to flow to the fuel rail. I did that, and it read about 42 psi, whether the vacuum line was attached or not. And yes, the regulator is getting vacuum at idle.
I assume that this means the regulator is bad and may be causing an over-rich condition at idle. This would be consistant with the low idle that improves when I let air in to the intake manifold through an open vacuum port.
Sound reasonable?
Thanks again,
Dave
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