festiva blows egi main fuse

[1garyz]

i had an issue a few months ago with the original fusible link burning out in the egi location, stalling the car. got good advise here and how to fix the issue, cleaned up the terminals popped in a pal fuse it ran great until yesterday on the way home it just stopped no warning. found the fuse blown again. replaced the fuse tried staring it, blew another fuse. got it towed home, with a volt ohm meter checked voltage @ battery and then the main fuse link panel same voltage. pulled the battery, overflow tank and carbon canister, looked at the harness no visible signs of wear pinching to cause a short. ohm meter to the harness side of the main fuse link no continuity so no short up to the main relay in the wiring harness diagram. put in new fuse turned on ignition, fuse did not burn out, went to crank the engine, no start up, looking again, another fuse blown. the ignition coil, ignition controller are on the main 30amp circuit looking at the wiring diagram. the distributor (crank pos sensor) are on this egi circuit along with the injectors, air idle control valve, canister purge valve. the fuel pump, air flow meter, fuel gauge are on the same circuit but controlled by the fuel pump relay. can anyone tell me how to proceed? are there any common areas to check or tests on these items i can make? i can find no damaged harness for a direct short (yet) but something is obviously shorting out when i crank over the engine. the next step is disconnect the air control valve check the harness back for a short then check the valve but what should me the resistance value testing it? same with the canister control valve. the harness from the injectors i doubt are the issue they look good and not in contact with anything and i have never heard of a shorted out injector. the next is the fuel pump relay under the dash and the wire run back to the fuse block lead, are they known to short out? how do you test it? then it is the run of harness to the fuel pump then the fuel pump itself, do they even short out? i am the original owner of this car and it has been well taken care of silicone sprayed the rubber and wiring harness so it is not some crisp brittle mess most car this age are so i am kinda doubtful i am going to find a harness issue but you never know. really hoping to hear some common problem areas from all of you in the hopes of making this an easy fix. the air flow meter was replaced a year ago with a rebuilt a-1 cardone unit because the vane in the original one was really stiff and worn out. i do not want this to be a 20-30 fuses blown circuit test and then replacing every unit i come across and things still do not work! please help me out here this is my commuter car and i really rely on this car.

[bravekozak]

Have your alternator tested.
Unplug it and start your car.

[1garyz]

thnx, will try tonight. one other note went to check timing a few day before it quit ground out the one pin sti plug the engine dies immediately, is something wrong with the ECU? the car had been running hotter than normal recently, new water pump, timing belt thermostat radiator so all this was in order but everyhitng i read to set the idle and timing when the car is warm you have to ground out this plug. the one has a signal for the tac this has to be the correct one but when i ground it instant shut off of the car which seemed wrong but i just ignored it and went on. now reading here and other sources something is not right will try the alt disconnect and start up but the other still looks suspect.

[tooldude]

Are you sure you have the STI terminal grounded and not the Tach? If not, unplug the Ignition module and test for continuity to the White wire which will indicate connection to the Tach terminal. It may be you're grounding the coil. Besides a short, the blown fuse issue could be caused by the fuel pump drawing too much amperage. Check the amperage if you can.

[1garyz]

THANKS, i am pretty sure with an electric ice pic when the car was running showed me a pulsing light and did not kill the engine. i will make a pic of the leads in that area and hopefully someone can show me the correct one but last time i went to check timing with what i thought was the sti terminal it shut the engine off immediately like i turned the key off. on warmer days under load (steep grade and low rpm) or after shifting gears and an rpm drop (auto trans) it immediately pings with any load which should be fuel starvation (lean) on non 80 degree days i don't have this problem i had been thinking the fuel pump may be wearing out after 210k on it......

pulled the bodywork access cover for the fuel tank last night and found the cable under that cover at sometime had been pinched and the outer tuf green insulator sleeve was holed and the black lead at a crimp (two leads down to one) was also thru to the copper crimp. whether it was touching and making a short is not clear but fairly likely, i am in the process tonight of shrink tube fixing that issue as a hopeful cause of the problem.

so in lieu of the fuse put an ammeter across the spades of the fuse block and see the amperage draw? i was reading the fuel pump only stays on for a few seconds with the key on then stays on once the car starts or is starting so with the car not running it may be hard to check? since i am there it is probably not a bad idea to replace the pump now anyway. i bet the filter has some clogging as old as it is, are there better pumps to replace the stock one with or just use a stock pump? i don't want one i put in and next year its DOA, any suggestions are appreciated. thanks for your input. my intent on the car is i am the only owner and retiring the end of the year. i want to do the aspire suspension upgrade and keep running the car till i konk out as my daily runner, love the car, really sad actually its DOA and not as yet sure whats the fix.

[1garyz]

alt checked ok at pep boys last night, found a suspect wire under the access cover to the fuel tank make a repair to that pigtail and i will try starting it again.

[bravekozak]

I had the same problem. Filthy rodents!

[tooldude]

Fuel starvation and pinging under load says one or both filters are clogged, the pump is failing, a line restriction, or a pressure regulator problem. Are you able to check FP pressure? The idea of checking Fuel Pump current was to see if that might be the cause of the blown fuse. If you opt to replace the pump and sock that becomes unnecessary but, either way, would give you a reference for any future troubleshooting. If you want to test the pump before replacing (change filters first), any amperage across the EGI fuse terminals could be subtracted from the total when the FP is activated. It runs continuously by jumping the FP test connector w/key ON - (GN/R & BKGnd wires, near the strut). Another easy check is to remove the pump relay and, on the connector, jump with ammeter: B+ wire (Y/BK) direct to the pump wire (GN/Y) - with key on. Or use a fused jumper wire from the battery to ammeter to GN/Y wire. B+ direct from the battery eliminates possible resistance in both Main and FP relay contacts but not the ground, for better accuracy. Also, when both relays are good, you can activate the FP by holding open the VAF vane, key on.

[1garyz]

thanks Tooldude, i will check amperes before i pull it out of the tank. have the fuel filter and pump/sock on order a denso pump from rock auto allot cheaper than anybody else for the pump and sock. went through allot of the harness found no chaffing or exposed wires, cleaned up some of the layout and added extra of the plastic corrugated split tubing in areas, cleaned connectors and so on. found a suspect wire on the mini harness that goes through the rear cabin access cover to the fuel tank it had been rubbing the fuel pump to tank cover and worn through the tough green sleeve they put over the harness put in some shrink tube to the one exposed wire and made a plastic sheet cover to lay over the pump to tank cover so in the next 23 years i do not have to worry about it. so how long do the pumps normally last? i doubt the 220k i have on the car now. the pump has never been pulled it has 220k on it so i guess it was well overdue.
i still need to get you the pics of the harness leads to verify the STI connector. the fuel pump override connector is the only 2 female connector plug there. i just jumper it to run the pump. the fuel filer has not been changed in 4-5 years so i am sure it is toast, i drive 80/mi a day to work so i put on the miles. the ammeter i am using is a ford tractor 60 amp ammeter, not allot of fidelity on the exact amperage, i have a clamp type ammeter for home electrical again on this i am not sure how precise it will be measuring a 12 v car system via induction. need to find a nice ammeter. my digital and analog volt meters all measure milliamps..... thnx for the very specific info and process. like i had said with the key on the bright copper fuse bar darkened but since it shuts off the pump in 3 or so seconds it did not have time to totally burn out the slow blow pal fuse. when i cranked the engine, no start. now when i check the fuse it is totally blown. more and more i believe it to be the fuel pump drawing too many amps blowing the fuse. my original problem was at a stop sign blowing the original 23 year old fusible link wire that blew because it was old and corroded. it was a lower amperage than the new pal fuse i used to replace it with, so it was enough to keep the dieing pump/clogged filter running. now 2-1/2 months later it has gotten worse and poof blown the higher amp fuse is my hope. there is nothing else on the circuit (less a shorted harness which i cannot find so far) that could blow the fuse other than it being a too high draw from the fuel pump. the wire from the VAF that signals the pump to remain, if i remember it is powered from the fuse box under the dash key switch, not from the EGI fuses circuit so it pretty much leaves it to the pump drawing too much. just to be sure a continuity check back from the correct plug connector to engine and chassis ground will tell me if i have a short in that circuit or not (which is doubtful and should not cause this fuse to blow). do you know the position of that connector on the plug or the color code for it? talking with you leads more and more to the fuel pump is/was the culprit on the first and the most recent fuse burnout. it is too coincidental i blow a fuse, then its good for another 2-1/2 months using the higher amperage PAL fuse replacement recommended here and now it blows again because i developed a short, if i originally had a short it should have taken out the new Pal fuse immediately not waited 2 months. learning allot here thanks. this was my original question posting when the pumps go do they short out or build a high load and take out the fuse? the answer seems to be a yes along with the fuel filter and pump sock clogging causing a higher draw taking out the fuse as well. this makes allot more sense than a magic short comes out of nowhere on this circuit and blows the fuse at two different times months apart when all i did was clean the contacts on the fusible link block put in a new fuse and things were back to normal until now. i could be wrong, but i kinda doubt it......... especially with what you are telling me.IMG_0969.jpgIMG_0974.jpgIMG_0976.jpgIMG_0977.jpg

[1garyz]

IMG_0964.jpg

[tooldude]

I believe the life of a fuel pump is best based on hours, not miles. You will accumulate many more miles per hour of operation on the highway than around town, so it's quite variable. I saw a repair article that mentioned a vehicle with a little over 300k on the original pump. I replaced my s10 pump at 200K, but the problem was actually the tank strainer, which was so clogged up that the suction totally collapsed it. Fuel quality is a big factor. The 60 Amp tractor gauge - not sure on that. It probably doesn't actually carry 60+ amps through the gauge itself. Some antique guages may have? The movement may read milliamps - be careful. OK, a suspect fuel pump so try this - unplug the connector at the fuel tank and see if the fuse blows at key-on. You could jump in cheapie blade fuses at the fuse box if you don't want to keep sacrificing PAL fuses. If the fuse doesn't blow, then it's probably the fuel pump drawing the extra amps. - I just noticed there is no heat damage at the tank connector or wiring in your pictures, but I'm not sure how many amps it would take to cause that

[1garyz]

thanks, i put in a fuse turned on the key, fuse did not blow, then i went to crank it no blown fuse, i went to crank it 3-4 more times no blown fuse, reconnected everything in the system save the connector into the tank for the pump cranked and no blown fuse, sound like i have an on the way out fuel pump. i am also replacing the fuel filter and the new pump comes with a new sock. i will then blow out the lines with air to be sure no restrictions or crud are there. will also replace the rubber lines at the tank and filter so they do not blow out after the new pump.... will you know the outcome, right now i am going over the harness, shielding, re-wrapping any and all suspect areas i find under the hood. i re-wrapped the wire in back you see exposed double wrapped and bought some .125 closed cell foam on e-bay to cover back over it like was there originally. this weekend will be the moment of truth. will keep you posted.

[1garyz]

from the picture can you tell me the connector for grounding out doing the timing i asked about earlier in the thread? the single white female connector is the tack signal connector the 2 female black connector plug is the fuel pump test override.

[tooldude]

^^Fuses not blowing as before sounds like the wire you repaired was a continuous short. Did you run the engine to see if the fuse blows again after time? The fuel pump may not have excessive amperage after all, and could be usable. I would test it anyway, but still, it's old. Testing current draw is a ballpark test IMO, mainly good for detecting early or late stage failure, but you need to know the spec on it or it's a bigger ballpark. Only a running scope pattern is going to reveal the internal condition. Without that facility, money is better spent replacing an old pump on a vehicle you daily depend on - what I did on mine. Now it's a judgement call on your part. ***Connectors - The STI has a black (according to the manual) single terminal connector in the section of harness by the fuel pump test connector and larger self-test connector. The RPM connector (I believe it's the white one in your picture) is a single terminal on a wire by itself and connected to a plug near the ignition coil.

[tooldude]

Oops, rereading what all you have done, I see you did NOT reconnect the fuel pump and test. I guess I was expecting that you would - read too quickly.