Engine Quit Has Spark & Electric

[Fred & Veda's boy]

1994 Ls 400 I Love it. Driving away from home , 2 miles out and the dash blinked and engine quit. I tried to start and no joy . It turns over normal. I checked Battery voltage , spark and fuses , all good. I don't here the fuel pump charging when I turn the key on. I changed the fuel pump relay. Again No joy. I had a tech guy come to read code after 2 hrs and several different attempts to get it to read . It said no code or unable to read ? I get the felling that it must be electrical , Any help would be gratefully appreciated.

[billydpowell]

do a search on 94's maybe you can find some help that way..

[Exhaustgases]

Check for good clean connections at the battery, even corrosion where the cable goes into the clamp, I had similar to your symptoms one time and it was the clamp to cable.

Check the battery voltage when cranking.

And when describing what happened, "no joy" doesn't mean much in technical terms to help figure out what the problem is.

If fuel pressure is there I don't think you would hear the pump, you need to do a fuel pressure test. A quick thing is to jumper at the test port (the one on the engine) to check the fuel pump, terminals FP and +B with a paper clip not too skinny a one. The ignition needs to be on for it to work.

This is for 90 to 92, I'm not sure how different the 94 is. I think the fuel pump relay for 94 is in the trunk?

[Fred & Veda's boy]

Thankyou for your reply. no Joy is my slang for " it did not work."

The trouble shooting I did was to First listen for the short pump charging sound that I always hear. And you are right it does not happen when it is a quick restart and the fuel system is up to pressure. The sudden blink of the dash lights and engine tach fall to zero seen as the lights were on .So I thought it must be electrical . Battery voltage after all the cranking was 12.6 static. I did not check while cranking. The engine cranks fast and strong. Then I pulled the spark plug wire and confirmed spark. Found the fuel pump relay under the air pump cover and replaced same . Still no result.

At this point because I out of the loop for 5 years being bed ridden, I'm just part changing. I don't care for that. I also had a gentleman tech type come with a diagnostic reader and got no code and can't read code and used a jumper to try a older method of the blinking light readout like the older Gm & ford use to have. Still unable to get a code. With the battery connection being the problem would it drop out that fast with the motor running?

[Exhaustgases]

With the jumper wire did you get the normal blinking light? A broke timing belt could be sudden and not start. I would remove the LH side wire / distributor cover and check the belt. There are other relays to. I don't have a 94 book, I think the electrical is different than 92 in many areas. The fast crank could be a broke time belt too.

[Fred & Veda's boy]

Thanks Bob. I have a Drs appt this am . But I'm going to check the belt before I go. The 94 is different than the 93 in some small ways. I have access to a 93 in storage from a friend. I have seen some post about the fuel relay being in the trunk and don't find anything on our 94 there on either side back there. I did find the marker fp relay under the air pump cover on passenger side forward . One person said to swap a/c relay with the ecm relay as they were the same. That did not seam to make sense to me . As I said ,I'm not up to speed on this unit yet. But I will null this out or die trying. :-)

[Fred & Veda's boy]

opps typo on pervious post not marker, but- toyota marked fuel pump relay.

[Fred & Veda's boy]

Bob

Timing belt is good. We had it done with a starter R&R last year. Water pump as well, in as much as we were told to do the starter these items should be addressed because of the major undressing of the engine to do the stater.

[Fred & Veda's boy]

Ialso checked battery voltage and cranking voltage. 11 volts cranking I'm going to pull rear seat after I check for fuel pressure with the key on.

[landar]

Tommy, you can also pull the duct work up to the throttle body and spritz some starter fluid into the throttle body while cranking to see if the engine will try to start.

[Fred & Veda's boy]

Thankyou, It does start with a shot in the intake and there is power to the fuel relay on the passenger side front under the cover marked airpump. I pulle the rear seat and checked for power at the two wires with the key on. no power. Remember this car gives a now code with one reader and Can't read with another. I don't know exactly what kind of reader however this same man read my neighbor's 92 toyota with success.

[Exhaustgases]

There is a circuit opening relay, and forget the diagram right off. You need to do the jumper thing I suggested to get power to those pump wires. You will not get power there with the engine not running unless you do the jumper thing.

"Gives a NOW code" so what is a now code? Don't need a reader for the codes on an obd1 system, you jumper some terms on the diagnostic plug.

http://www.lexls.com/tutorials/intro/codereading.html

And it runs with some kinda fuel, so then you know for sure its a fuel problem then.

[Fred & Veda's boy]

Sorry Bob , long day Correct now with " No Code and the second read out was unable to read at least that is was he said. I also made up a small jumper wire for him and he attempted to read the blinking light system as I just read though.So now I know exactly what he was doing. With the jumper wire is when he said he was unable to get any blinking light. With his code reader plugged in standard he said it read no code. That is the best I remember. I was wondering could I put 12 volts to the pump connection at the rear top of the back seat (now removed) to see if pump will run or if there is pressure already built up will it be held out or off? I don't know if i'm thinking correctly?

[landar]

Tommy, here is a circuit diagram of the power to the fuel pump. Study it carefully. You can basically bypass the "circuit opening" relay and send power directly to the pump by jumping the +B and FP pins on the breakout connector in the engine compartment.

[Fred & Veda's boy]

Thanks Randall,

The fuel pump relay under the air pump cover on passenger side forward fender well has a 4 blade connector outside back pin has 12 volts on it and direct inboard pin has 5 volts on it . With in switch on, this is curious to me. On the above diagram the item marked "check connector"labeled in the engine compartment?

[Fred & Veda's boy]

Randall I seem to have miss read small print .Your post read breakout connector. I saw check connector?

[landar]

Yes, the check connector is in the engine compartment. It is actually labeled "Diagnostics" on my 92. I am pointing to it in the attached picture.

Take the cap off and look at the inside of it for the connector pinouts. You will see "B+" and "FP". That's what you want.

[Fred & Veda's boy]

Randall

Thanks so much . A quick bite and i'm off to the shop. Will contact you asap

Tom

[Fred & Veda's boy]

Randall I installed the jumper B+ fp. Igition on I get nothing . no start and no noticeable noise from the pump.

[Exhaustgases]

Now you need to study the wire diagram that was posted here.

See if you get power at all points that feed to the fuel pump. As you said you didn't get power at the pump.

If you wish power up the pump, I'm sure that is not the problem. The power runs through that fuse, then the EFI relay so you

need to check them. Even the ignition switch is suspect in the diagram, you have to check all connections for power back to the ignition switch starting from the pump. And that is with the jumper installed in the plug. I say first do you get 12 volts at that B+ with ignition on? If not next go to the EFI relay. If B+ has 12 volts go to fuel pump relay and check at its terminals.

[landar]

I have come across some posts that seem to suggest that the fuel pump relay may be in the trunk near the fuel filler cap on a 1994. Especially since you mentioned you have an 'air pump' where the relay would normally be. You might want to research this a bit more.

[Exhaustgases]

What happened to this one? I'd like to know how it all went.

[Fred & Veda's boy]

Well I'm still deep in it. The jumper across B+ to FP and I have 12 volts to the EFI with and without the jumper. I also have 12 volts to the relay marker fuel pump relay. I see on the diagram fusible link and is said to be close to the battery. I don't seem to find it . I was wondering if they show like the ford links that wrinkle up noticeably when blown? Where exactly is it located? I did mention that I put 12 volts to the pump and I could hear it running but i wouldn't start.

[landar]

So, the engine tries to run when you crank and spray starter fluid but not when you purposely jumper the fuel pump and hear it running? If you are absolutely sure the fuel pump is powered then you need to get on the fuel rail and check for pressure with FP and B+ jumpered (pump motor powered). I would check for voltage to the pump at the rear seat as you did before just to be sure. The motor may be spinning but something could be wrong with the pump assembly such that there is no pressure.

[VBdenny]

In my experiences problems like Tommy described are of an electrical nature 90% of the time. Myself? I do a lot of electrical checking before I ever get into the fuel. Never had a fuel filter or fuel pump fail that the chunging was unrecognizable.

Consider such things as the ground wire that grounds the engine (which is mounted on rubber mounts) to the frame. Oh man, I had them corrode and cause weird things even before the electronic age. Also, not sure if 94 was the same but there is a major bundle of wires in the drivers side trunk hinge that flex every time the trunk is open. I'm not exactly sure what wires are in there but when one broke on my 90 LS400, the car barely ran. There were maybe 8 wires in there so something for thought.

Hopefully this may help some.

Denny