87 Civic Power-loss under load
12-04-2013
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87 Civic Power-loss under load I've posted about this before, chased the problem for about a year, and finally got it resolved.
The symptoms were: Starts, idles, and runs fine. Has plenty of power (at least for an '87 1.5L carbureted vehicle)
When under a sustained load, like trying to accelerate up a long hill, will hit a spot where it loses power in a big way. Will barely run, and even with several downshifts won't run even half decent. Easing off on the accelerator does not help, but...
Let off the gas for a count of five, and power is restored and it runs fine.
This seemed to be an obvious fuel problem, so first steps were changing both front and back filters.
Next the fuel pump (it seemed better but not fixed). Actually seemed OK for a while but gradually got worse again.
Had carb rebuilt - no change
Replaced distributer and reset timing - no change
checked compression -good but slightly low on #1. (it has about 250k miles on it)
replaced ignition wires and plugs - no change.
Checked for vacuum leaks, found and fixed some - no change
Found that tank was building vacuum. Dealt with partially plugged charcoal filter - some improvement but not fixed.
Checked fuel pressure and volume from new fuel pump - slightly below spec. Replaced with genuine Honda replacement fuel pump - No change.
Checked valve adjustment and found that the aux valve for #1 was a little tight. I suspect this may have been sticking when under load. Adjusted valves. This seemed to make some difference, idle improved, and rechecking compression showed good and even on all cylinders.
Began having different (inconsistent) idle issues. Noticed that float setting was off. adjusted but then noticed that float setting not staying where set. What could cause that???
Disassembled carb and found...
First the "rebuilder" did not seem to have replaced carb gaskets. It looked like maybe the carb had been dipped in carb cleaner, bench tested (maybe) and returned. Any intermittent problem in the carb might have passed a bench test.
Upon close inspection, there was wear like a small gauge and a "catch point" where the float contacted the needle. The needle and float were intermittently sticking and binding at this point.
Replacing the needle, seat, and float restored proper carb function and the problem seems fixed.
I do suspect that I am still occasionally getting a little sticking on the #1 aux valve. These can be changed without pulling the head, so I am probably going to try to find a used one and see if it changes the remaining minor and infrequent "stumble." (Anybody out there have a trashed head or engine for an 85-87 1.5 that they would be willing to pull one of the aux valve boxes from? Note that 88 and later 1.5 has a completely different head and nothing from it would work.
I got caught with the old "assume" issue. Since I had the carb professionally rebuilt, I assumed that they had actually done that and that I could eliminate the carb as the source of the problem.
The gouged float tang was the main culprit, but the problem was complicated by the partially plugged charcoal canister causing tank vacuum and the weak fuel pump.
Anyway- much frustration and more that a few dollars spent, it now runs as good as any 1987 civic 1.5L 5-speed still on the road.
P.S. Honda has (or had) a float/needle set that would have been perfect, but it is discontinued and there is no old stock available. I found a Honda dealer that listed the part but after accepting my order, they waited three weeks, then told me it was no longer available.
There are aftermarket rebuild sets with the needle and seat and there are after market floats available - each of these sells for about the same price as the discontinued Honda part.
It is getting harder to keep these old Honda's going as some parts are getting really scarce. I think I got the last three Radius arm bushings in the country and one of mine was good enough to reuse for a set of four to replace both radius arms.
None of the vacuum valves for the complicated computer/vacuum/carburetor/distributer are available from any source. It is even many of the tire manufacturers have discontinued the tire size. (175R-13)
Cheers!
May none of you ever experience a problem like this, but if you do, maybe this saga will help :-)
The symptoms were: Starts, idles, and runs fine. Has plenty of power (at least for an '87 1.5L carbureted vehicle)
When under a sustained load, like trying to accelerate up a long hill, will hit a spot where it loses power in a big way. Will barely run, and even with several downshifts won't run even half decent. Easing off on the accelerator does not help, but...
Let off the gas for a count of five, and power is restored and it runs fine.
This seemed to be an obvious fuel problem, so first steps were changing both front and back filters.
Next the fuel pump (it seemed better but not fixed). Actually seemed OK for a while but gradually got worse again.
Had carb rebuilt - no change
Replaced distributer and reset timing - no change
checked compression -good but slightly low on #1. (it has about 250k miles on it)
replaced ignition wires and plugs - no change.
Checked for vacuum leaks, found and fixed some - no change
Found that tank was building vacuum. Dealt with partially plugged charcoal filter - some improvement but not fixed.
Checked fuel pressure and volume from new fuel pump - slightly below spec. Replaced with genuine Honda replacement fuel pump - No change.
Checked valve adjustment and found that the aux valve for #1 was a little tight. I suspect this may have been sticking when under load. Adjusted valves. This seemed to make some difference, idle improved, and rechecking compression showed good and even on all cylinders.
Began having different (inconsistent) idle issues. Noticed that float setting was off. adjusted but then noticed that float setting not staying where set. What could cause that???
Disassembled carb and found...
First the "rebuilder" did not seem to have replaced carb gaskets. It looked like maybe the carb had been dipped in carb cleaner, bench tested (maybe) and returned. Any intermittent problem in the carb might have passed a bench test.
Upon close inspection, there was wear like a small gauge and a "catch point" where the float contacted the needle. The needle and float were intermittently sticking and binding at this point.
Replacing the needle, seat, and float restored proper carb function and the problem seems fixed.
I do suspect that I am still occasionally getting a little sticking on the #1 aux valve. These can be changed without pulling the head, so I am probably going to try to find a used one and see if it changes the remaining minor and infrequent "stumble." (Anybody out there have a trashed head or engine for an 85-87 1.5 that they would be willing to pull one of the aux valve boxes from? Note that 88 and later 1.5 has a completely different head and nothing from it would work.
I got caught with the old "assume" issue. Since I had the carb professionally rebuilt, I assumed that they had actually done that and that I could eliminate the carb as the source of the problem.
The gouged float tang was the main culprit, but the problem was complicated by the partially plugged charcoal canister causing tank vacuum and the weak fuel pump.
Anyway- much frustration and more that a few dollars spent, it now runs as good as any 1987 civic 1.5L 5-speed still on the road.
P.S. Honda has (or had) a float/needle set that would have been perfect, but it is discontinued and there is no old stock available. I found a Honda dealer that listed the part but after accepting my order, they waited three weeks, then told me it was no longer available.
There are aftermarket rebuild sets with the needle and seat and there are after market floats available - each of these sells for about the same price as the discontinued Honda part.
It is getting harder to keep these old Honda's going as some parts are getting really scarce. I think I got the last three Radius arm bushings in the country and one of mine was good enough to reuse for a set of four to replace both radius arms.
None of the vacuum valves for the complicated computer/vacuum/carburetor/distributer are available from any source. It is even many of the tire manufacturers have discontinued the tire size. (175R-13)
Cheers!
May none of you ever experience a problem like this, but if you do, maybe this saga will help :-)
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