90' Corolla fuel pump not priming. - Toyota Nation Forum : Toyota Car and Truck Forums

fspell220 · 10-26-2009, 02:31 PM

Hi I'm new to Corollas. I recently purchased a 1990 Corolla dx. I think it has the 4afe motor, idk. It's 16 valve dohc, fuel injected. Mileage is 116,000. I got a good deal on it, $300. The timing belt was broke and it had a few burnt valves. I purchased the valves, valve seals, head gasket, intake gasket, exhaust gasket, fuel injector orings, and timing belt. I cleaned head almost to new condition lapped the valve seats installed new valves and valve seals, reassembled the upper engine, install timing belt. Runs great @ idle. but doesn't have hardely any power. Checked compression, I'm running about 120 on all four cylinders, so im spot on there. I checked my timing marks on both cams and the crankshaft, even though I marked them before dissassembly, and I'm good. I noticed that the pump isn't priming when I turn the key to the on position. I check my pump by bridging fp and +b on the computer terminal. the pump is pressurizing the fuel line. I checked the relay in the fuse box, it is opening and closing. Also, there is a "ground wire" that is black with one yellow stripe, it has a bolt connection on each end and has a plastic connection in the middle, it is about 14" long. Idk, where this wire goes, it was off the car before I bought it. Any help would greatly be appreciated.

Donald · 10-27-2009, 01:28 PM

I don't understand. You say the pump isn't priming, but then you say it is pressurizing the fuel line??

??

I just bought a '93 Geo Prizm, and the guy said it had a bad pump. When I pulled the pump out, I found that the tank and the pump are very rusty.

The gas cap was missing, and water apparently got inside the tank and did it's evil.

So! For a $7.00 gas tank cap, the tank and pump are worthless.

fspell220 · 10-27-2009, 05:01 PM

No, I said when I turn the key to the on position, before cranking it, it does not prime (the pump isn't priming). I then tested the fuel pump by bridging terminals fp and +b and the pump is fine, with a pressure reading of 32 psi. I've checked all fuses and all relays, all are fine. Was just wondering if anyone else has had a similar issue and wondering if there's something I'm over looking. I know @ this point it has to be an electrical issue. Could the ignition switch be bad possibly. I'm outta ideas. I really don't want to have to test lines with a multimeter all the way back to the tank which I will have to drop most likely. Anyone else got any ideas. If not then I'm just going to perminently bridge those two above mention terminals, cause it will @ least run great when they are bridged.

90 GP · 10-27-2009, 06:37 PM

Here is a link to a wiring diagam. Check out Figure 4 which shows EFI and ignition switch. Use a digital ohm/volt meter to trace out circuit.

http://opc.mr2oc.com/online_parts_ca...CorollaFWD.pdf

Donald · 10-27-2009, 08:53 PM

Quote:

Originally Posted by fspell220

No, I said when I turn the key to the on position, before cranking it, it does not prime (the pump isn't priming). I then tested the fuel pump by bridging terminals fp and +b and the pump is fine, with a pressure reading of 32 psi. I've checked all fuses and all relays, all are fine. Was just wondering if anyone else has had a similar issue and wondering if there's something I'm over looking. I know @ this point it has to be an electrical issue. Could the ignition switch be bad possibly. I'm outta ideas. I really don't want to have to test lines with a multimeter all the way back to the tank which I will have to drop most likely. Anyone else got any ideas. If not then I'm just going to perminently bridge those two above mention terminals, cause it will @ least run great when they are bridged.

The circuit opening relay needs a signal from the ECU telling it that the igniter is firing, before the fuel pump will work.

That is why you need to bridge the +B and FP terminals with the ING switched on, to test the pump, without running the engine.

If the pump works when you do this, and not work when you try to start, then you have either a bad signal to the circuit opening relay, or a bad relay.

fspell220 · 10-28-2009, 02:34 PM

Cool man, thanks. So, what would be some things I would need to check for the signal to the relay circuit? I'm sorry to sound ignorant, but I've never had this problem before and have never worked on any toyota period. lol. Oh, I did read up on retrieving codes. No codes were stored, only code was normal operation. I love the fact that I don't have to by an expensive obd2 scanner in order to diagnose my car.

90 GP · 10-28-2009, 06:36 PM

You don't need to drop tank to get to fuel pump or wiring for it. Remove back seat bottom cushion and you can see the access panel and wiring for fuel pump.

Donald · 10-29-2009, 09:57 PM

If it runs, and you have 32psi, the pump is not your problem.
Is your ignition timing correct?
I would check that, and if that is OK, I would recheck the timing belt setting.

Drainx · 10-30-2009, 06:43 PM

I have a similar problem. Only it starts fine the first time in the morning, but if you drive around, then park it, come back and try to start it, it idles fine then just stutters out. If I wait a few seconds I can hear a quiet 'ka-thunk' noise coming from somewhere, then the car starts fine. I asked a friend about it, he said something about a fuel pump relay in one of the black fuse boxes under the hood. Which one of these things am I looking for?

Donald · 10-30-2009, 08:42 PM

The circuit opening relay that controls the fuel pump is under the center console trim, to the right of the drivers foot well. It is beside the ECU.

fspell220 · 11-05-2009, 01:28 PM

Thanks for all the replys guys. I appreciate it. I have double checked everthing. timing belt/marks are correct. Checked timing while car was running with light, spot on, so my dwell angle is correct. Great spark. Runs great. No problems other than the fact that it won't prime or run unless I bridge the 2 previous mentioned terminals. It even drives good, plenty of power. I tried removing the back seat cushion to access the pump, but that doesn't give me access to the pump only the sending unit which I find weird that the pump is seperate from the sending unit but ok. My pump is located farther back on the tank and there is no other access in the trunk or anything so it will have to be dropped. I've checked all relays, all fuses and fusible links, it has to be in wiring circuit from the ignition switch to the pump. I havent had a chance to trace wires yet but will do so as soon as I drop the tank. I'm gonna go ahead, while it's dropped and replace the pump and strainer while it's out even though its pumping good now, ya never know, it may decide to fail a couple of months down the road.

fspell220 · 11-09-2009, 04:59 PM

Problem solved. There was a wired chewed into right before the harness went to the tank. Apparently field mice had made a nest on top of the tank @ one point. The car has sat for about 2 years, so that makes sense. So, now my pump is priming when the key is switched to the on position. Also, I removed the injectors and cleaned them. They were pretty dirty. I never cleaned them thorougly when I had them out before, power seems normal, @ least it climbs up hills with no problem. It also idles and runs alot smoother. Thanks for all the help guys. Maybe this will help someone else out in the future.