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My 1992 civic si hatchback recently broke down. One morning I went to start it and it ran for about 5 min then shut off. I started it again and it ran for a shorter amount of time then shut off. Now it won't start at all. I used a fuel pressure tester and found I had no fuel pressure. After replacing the fuel pump and filter still no start. I can hear the pump buzzing but it sounds a little rough. I opened the filter to see if any gas was in it however there was none. There was no fuel in the filter. Im thinking it could be the main relay not activating long enough or it could be frozen fuel lines as I live in colorado and it has been very cold these past few weeks.

 
Rep Power: 518

Use a meter or test light to confirm both power and ground at the pump/tank connector whenever the pump is supposed to run.


Gasoline does not freeze.
Water in the tank would freeze, did you check for that while the pump was out?

 
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Well residual water in the gas in the lines could freeze right? I will test the pump tomorrow.

 
Rep Power: 518

Residual?
If there was water in the tank, you would have been having running problems before it quit.


You had no fuel flow to the filter in the engine compartment, so I'd then disconnect the line at the tank and see if the pump is actually doing anything there.

Assuming no flow, then reconnect the line
and test for power and ground at the tank unit to prove the car is trying to operate the pump correctly. (may need a wiring diagram to get correct wire colors)

If there is battery power and ground at the unit, then you must have a pump issue: electrical problem (maybe pump was wired backwards?) OR a fluid connection problem, like the pump blew a line off to a fuel tube.

 
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Alright so I opened the line just above the pump and there was no fuel in it, the bolts weren't even wet with gasoline. I checked the connection with a multimeter and was getting about 2 volts for half a second then nothing. The battery has 12.4 volts so I'm thinking the ground is bad? Or the main relay is the issue.

 
Rep Power: 518

Well,
One or two seconds sounds about right if you only turn the key to on, that's the pump prime period. Pump should run continuously while cranking the engine and while running.

2v ain't right unless your meter is awful slow to react....or your meter is set on the wrong scale, if it's that type of meter.

So go with 2v for a sec.....Why is it only 2v?

Couple ways to go about checking.....

Connect meter to a known good ground (battery neg post if you have enough wire) and see if you still see 2v on the hot wire at the pump when you turn the key on and crank it.
Then test the ground.....same way, just move the test lead to the ground wire and crank it....if ground is good the meter should stay at zero volts. If voltage goes up several volts then the ground is a problem..


Or go to the PGMFI main relay and test voltage output on the pump wire (check diagrams again for correct colors), see if it is 12v when the relay turns on.
(I might start there, as main relays have always been a problem area at least once in the cars life.)
You could use a jumper wire to supply battery voltage to the wire at the relay plug and see if pump works.

 
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Alright thanks so much, I will not have time to test this until the weekend so ill post back then. I also have the SI so I have MPFI. I also went through the main relay and re-soldered all the terminals.

 
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OK so I had spare time to go and do some tests. I found that with the fuel pump cable unplugged i am getting 11.6 volts. However the battery is reading at 12.3. I also tried another ground and got the same reading, 11.6 volts. looked in the filter again and no fuel inside whatsoever. After putting in a couple gallons of gas I wired the pump directly to the battery. I checked the line right at the pump assembly and it seemed to be slightly wet with gas. but not much. Checked the filter and it seemed none was in there once again.

Checked main relay ground and it was fine. checked the ground wire near the thermostat and it was fine. Also started to noticed that when I would crank the engine it acts like the battery is dead even though its reading 12.3 volts. I am completely stumped!!

one thing I forgot to mention is the previous owner installed a kill switch that turns the main relay on and off.

 
Rep Power: 518

Weak battery?

Unplugged? When I test stuff like this, I leave the items connected so there's still a load on the circuit. I backprobe the connector terminals, usually using paper clips or T pins.

If you had a poor connection in the circuit, that might show decent voltage with no load (unplugged) but the poor connection (high resistance) would not allow sufficient amperage through to operate the load.
A voltmeter is not a significant load.
A headlight would be a load, a 55W bulb would be about a 4 amp load.

So you really should consider more than just simple volts when testing.
Anyway.....

You supplied the pump with power and ground directly from a battery, and the pump SHOULD be able to make fuel squirt out of the pressure line (pressure line disconnected and open). "Slightly wet"? You need to double check this. If it cannot pump and build pressure, you probably need to take it out of the tank to see why.

Again, you can show volts but if it doesn't have the amps to back it up, volts alone don't do much good.
Sounds like the battery is probably weak (ran down), you probably should put it on a charger for a few hours before it goes dead. Then see if it cranks better.

 
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ok Im kind of new to using a multimeter but I'll figure it out, I'll measure amps and volts while under load next time, not sure I have a battery charger, could I just jump it? I'm guessing not. Anyway I'll also run it with the line disconnected and see if I get good flow, is it possible I have a broken line somewhere and the pump can't pressurize the system because of it? Again thank you so much, I'm a senior in high school and am seriously thinking of going into auto mechanics.

 
Rep Power: 518

You'd have to have a meter that can measure amps.
Measuring volts while the circuit is loaded can be more useful than a real amp reading.
Battery needs time to charge, and at a higher voltage than the system at rest. You'd need to have another car running for a good long while to charge your battery up with jumper cables.

OTOH if you KNOW your car is gonna run, you can jump it to get it started and drive it around for an hour or two. But your car doesn't run right now, and if you let a weak battery sit in the cold it can freeze, that will ruin it. (A fully charged battery won't freeze.)

Borrow a charger?
Sure. If it happened to be the problem right now, I'd expect something like that to be inside the tank.