Community Forums

clyon51 · 04-24-2013, 12:04 PM

Quote:

Originally Posted by tek_ryter

Yes. When I turn the key I can hear the pump.

A code reader would be a good idea to have and keep anyway, but I would first check for spark at the plugs when cranking. If good, I would want to know there was sufficient fuel and pressure at the rails to rule out faulty pump or clogged fuel filter(s).

Since that battery was sitting dead for that long and depending on it's age, it's most likely in bad shape.

tek_ryter · 04-24-2013, 12:42 PM

Thanks. I'm pretty sure the battery is going bad. I'll check for spark. You're right, a code reader is a handy thing to have and reasonably priced these days.

tek_ryter · 04-24-2013, 12:45 PM

I thought the pump only ran for a few seconds when the key is in the ON position, prior to going to START.

subford · 04-24-2013, 01:56 PM

Quote:

Originally Posted by tek_ryter

I thought the pump only ran for a few seconds when the key is in the ON position, prior to going to START.

Yes you are correct. They only run for one second each time the key is turned on. Your problem is the clock is not running in the computer.
You more than likely have a bad computer. The code reader is a good thing to have but it will not help you in this case as it will do nothing when you try it.

You more than likely have bad caps in the computer but the crystal may have broken loose also but not likely and it is a easy fix. The two new caps will only cost about $1.00 and you can solder them right in as other have or re-solder the crystal. Then you will be good to go and the code reader will now work also.

tek_ryter · 04-24-2013, 02:07 PM

Great! I will definitely check that. Thanks.

tek_ryter · 04-24-2013, 02:20 PM

I'm guessing these capacitors can be found in an electronics store like Radio Shack.
?

subford · 04-24-2013, 02:52 PM

Quote:

Originally Posted by tek_ryter

I'm guessing these capacitors can be found in an electronics store like Radio Shack.
?

I am not sure what Radio Shack has any more.
Most of my contacts have bough the capacitors from Digi-Key when replacing these capacitors.

By the way here is a link you might want to read:
http://www.ford-trucks.com/forums/12...e-problem.html

/

tek_ryter · 05-31-2013, 10:59 PM

Well... I'm still working my engine start problem. I've done several things but still no luck. I replaced the battery, in-line fuel filter, verified there was spark, visual inspection of the EEC IV (capacitors looked to be intact). I hooked up an OBD 1 scanner with the following results: self-test-111, KOEO-543 (Fuel Pump Secondary Circuit Fault). The fuel pressure tester read 10 psi at the fuel rail fitting. I'm not sure where to go from here. With the low fuel pressure I'm thinking it might be the fuel pump. Maybe a relay? Any advice will be greatly appreciated!
In my original post I noted that it sounds like the pump runs continuously with the key ON.
Thanks.

subford · 06-01-2013, 06:41 AM

If the fuel pump runs "continuously with the key ON" 98 times out of 100 times you have a bad Computer.
The other two times that it is not the computer the fuel pump relay is stuck closed or someone has wired it to run all the time the key is ON.

But if the fuel pump "runs continuously with the key ON" you should also have 42-45psi fuel pressure at the fuel rail (manifold) and not 10psi.

So it sounds like you have maybe two problems keeping it from starting.

The CM code 543 (Fuel Pump Secondary Circuit Fault) most of the times means you have a bad fuel pump.
The other times it is a fuel pump relay not closing when told to do so by the computer or it is stuck closed.

But if the fuel pump relay was stuck closed the fuel pump would run all the time with the key ON or OFF.

tek_ryter · 06-01-2013, 07:16 AM

Quote:

Originally Posted by subford

If the fuel pump runs "continuously with the key ON" 98 times out of 100 times you have a bad Computer.
The other two times that it is not the computer the fuel pump relay is stuck closed or someone has wired it to run all the time the key is ON.

But if the fuel pump "runs continuously with the key ON" you should also have 42-45psi fuel pressure at the fuel rail (manifold) and not 10psi.

So it sounds like you have maybe two problems keeping it from starting.

The CM code 543 (Fuel Pump Secondary Circuit Fault) most of the times means you have a bad fuel pump.
The other times it is a fuel pump relay not closing when told to do so by the computer or it is stuck closed.

But if the fuel pump relay was stuck closed the fuel pump would run all the time with the key ON or OFF.

Thanks for the quick response. It looks like either way, it's going to cost $$$. I have the schematics, so I guess I'll get my multimeter out now and check the fuel circuits and components. After that, I guess I'll get my wallet out!!

Well, on the positive side, at least I'll have a better understanding of my Winnebago!

Thanks again.

tek_ryter · 06-01-2013, 08:00 AM

The more I think about it, I'm leaning towards a failing fuel pump. If the fuel pump is not putting out sufficient pressure, then the relay wouldn't trip, and if the relay doesn't trip, then the pump will keep running. Momma told me there'd be days like this!

subford · 06-01-2013, 08:10 AM

Quote:

Originally Posted by tek_ryter

The more I think about it, I'm leaning towards a failing fuel pump. If the fuel pump is not putting out sufficient pressure, then the relay wouldn't trip, and if the relay doesn't trip, then the pump will keep running. Momma told me there'd be days like this!

The fuel pump relay does not trip.

The fuel pump relay has nothing to do with fuel pressure.
The fuel pump relay is either on or off and is operated by the Computer grounding the coil of the relay.

The computer grounds the coil of the fuel pump relay for one second each time it sees a PIP pulse from the distributor or when the key is turned on.
The fuel pump runs at no other time.

jamesrxx951 · 06-01-2013, 02:56 PM

Look inside the fuel tank also. In several cases that I have run into, there was low pressure due to the filter sock being plugged up. Some of the earlier tanks would either rust or there is just excessive debris in the tank and the filter sock would plug up quickly. A few years ago we had a motorhome come in where the customer installed 2 new fuel pumps within a short period of time. He brought it to us and I found excessive debris in the tank with clogged filter socks. There are companies out there that will clean the tank and spray in a coating to keep any other rust from flaking off. Much cheaper than a new tank.

Excell · 06-02-2013, 08:50 AM

How much gas is in the tank ?Before you take it off think about that ,it is going to be heavy .If you are testing the pump pressure properly ,and you are sure there is power at the pump you have a pump problem .Make sure you have battery voltage at the pump .A green connector would not surprise me . low voltage will give low pressure .