??? driveability issues - 1985 L98
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Race Director
Joined: Aug 2000
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??? driveability issues - 1985 L98
my son's 85 (L98) has some driveability issues. seems that the car starts OK, in fact it starts immediately, but bogs, and basically develops no power under load. i've been trying to help provide diagnostic help long distance - over the phone, but i thought i see what the forum can offer. he has limited experience, but has checked the ignition system, and check for a clogged cat, and both seem OK, (but i can't rule out a timing advance problem). i have told him that the next thing would be the fuel system. i'm thinking there may be a fuel pressure issue - either a bad regulator, a weak fuel pump, or maybe even a partially clogged filter. injectors cleaned and serviced about 3 years ago. i do know the fuel filter has a few years and miles on it, and the fuel pump was replaced about 8 years ago. until he gets a fuel pressure test gauge, i told him to check the vacuum lines for anything broken or disconnected. being a 1000 miles away, trouble shooting seems to be part of the problem. any comments or suggestions??? TIA...
Good chance it's a fuel delivery problem.
Instructor
Joined: Jul 2011
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unfortunately, just checking pressure is not going to be enough, you have to do a fuel volume test. with the pressure gauge attached, and car running, pull the vacuum line off the pressure regulator. pressure should increase. rapidly accelerate the engine, while watching the gauge. the pressure should not drop below 2 psi. if it does, replace the fuel filter and retest. if it happens again, replace the pump. if the vacuum hose to the pressure regulator has gasoline in it, the reglator is leaking and shoud be replaced. also, double check that the fuel filter is installed in the correct direction! i have, unfortunately, found someones car with the same problem that had the filter installed backwards. check all the fuel lines for kinks. the line could have gotten kinked while the filter was being replaced, or in another spot from hitting a rock or some other road debris. if the fuel system checks out ok, i would look at a restricted exhaust, check the cat, AND the muffler. good luck
