1993 Chevy P30 fuel pump help

[Tommy_U]

Hi All - I have a 1994 Fleetwood Southwind on a 1993 P30 chassis. Got back from 4th of July weekend and was pulling into storage the next day and just as I placed it in Park and set parking brake the engine died. After that it would not start and had 3/4 tank of gas. I used some starter fluid and it will start so it is a fuel delivery problem. Also I was not hearing the fuel pump. I am having a hard time locating the fuse / relay for the fuel pump. I have checked all fuses I can find any bad, all seem to be good. I have a Chevy service manual but it is terrible and has very little info. Does anybody have a wiring specs for a 1993/94 p30? I was having trouble with my gas gauge also so I dropped the tank and replaced the whole unit assuming it was a bad fuel pump but possible electrical. I need to start tracing the wires and checking them / possible bad ground or broken wire. The plug to the fuel pump has 3 prongs, I assume it is ground, power for the pump and sending unit signal. Does anybody know what the voltage should read for the 3 wires and which should have power when the ignition is on? Any help would be greatly appreciated cause I have a vacation planed Aug 1st and need to get this solved asap. Any suggestions on what else to check would be greatly appreciated.

[summerwinds48]

Here's my experience with the fuel pump in my Itasca '94 P30. The fuel pump went out 3 times in the past 3 years, mainly caused by ethanol corrosion to the sender unit connections, and possibly a rusty ground on top of the tank. The sender unit was finally replaced at the last failure, as the gas guage was also showing erroneous readings. Been running fine for over a year now, and I also use CRC fuel treatment (1 oz. per 5 gals.) with the ethanol gas. However, the new sending unit was only for a 60 gal. tank and I have a 78 gal. tank. Those sending units are hard to find. Just have to remember that my fuel guage is measuring only the top three fourths of the tank, and the bottom of the fuel pump is at a quarter tank. Will be searching for the full 78 gal. sender unit to get the fuel management back to normal, but will need to drop the tank again to replace the sender unit.

[Tommy_U]

thanks for your input. I did find that auto park is just coincidence that the light is on now and a whole separate issue. the fuse that keeps blowing is connected to the ignition and mainly the small acculator the released the gear selector when you press on the brake pedal..... now I will need to find out why it is causing a fuse to blow. I am going to just replace it and see if I still have a problem after. I see I have a bad wire leading to my fuel gauge. When I disconnect the harness near the transmission coming from the back my needle starts moving up and down depending on how I am moving the wires. I changed out the temp sensor and I think I solved the crappy rich running when cold.

[More_To_See]

My memory of auto park is that it's a subsystem not having much to do with anything else on the rig. When you go to park there is a cam operated switch way up above the front wheel (and outside) that takes away power which had been maintaining hydraulic pressure to keep that spring loaded brake shoes off the drum. That cam operated switch controls a solenoid and does not carry high current. So I'm not quiet sure how auto park has anything to do with your problem - but then I'm working completely from memory right now. I'll have to dig into it a bit.

[Tommy_U]

kcny, - thanks for the link

the part at the bottom of the steering wheel column that was super hot was the Transmission Shift Brake Interlock Solenoid

[kcny]

Here is a link to the Autopark library, it should have all the info you need:

http://www.oemys-performance.com/j71autopark.htm

[Tommy_U]

More To See- - you were a little curious as to why the fuse blew as was I. I finished putting all the brackets on the fuel fuller hoses and started her up and again seemed to be running quite rich and surging a little bit so I headed home to grab a few things then head over my dads house with it. I parked backwards on the left side of the street when I got there and soon as I put it in park pop, it blew another fuse. I hopped out the drivers door and pulled the fuse and put a new one, turned the key and nothing. It would crank over but not start. When that ignition fuse blows it cuts power to the throttle body injects and possibly to the spark plug. I am not sure cause I didn't check for spark. I put another fuse and only turned the key and pop, it blew another fuse. After that I tried putting the coach in neutral, replaced the fuse and then it started right up. I put it in reverse, and then drive and all was good so I jumped out and put wheel chocks just in case. I took off the cover on the column so I get at all the wires and plugs. I also noticed that my Auto park light was on even when I put it in gear, but not when the fuse was pulled out, auto park would go out soon as I selected drive with the motor not running and I could hear the hydraulics to the auto park pump up, then released when I put in park. This has lead me to believe possibly I have a bad auto park switch on the column. At this point I was so frustrated I decided to put on my new springs cause I had a bad air bag and decided to go with the heavy duty rated spring. While I was working on that for several house and of course had my new set of trial and tribulations I had used the hydraulic levelers to lift one front wheel off the ground and placed jack stands under the frame. Long story short fishing with both side of the springs and after cleaning up all that mess of tools I needed to lift the coach a bit to remover the jack stand. I realized I had left the ignition on that whole 3 1/2 -4 hrs. I just so happened to touch the little acculator at the bottom of the column that when the brake is applied it allows you to move the selector out of park. It was hot as the dickens and I almost burnt my self. I finished cleaning up and then started to investigate this acculator. It was still hot as heck. I unplugged a single wire and would make it move. I then put the ignition on and started it up. Moved the selector from park to reverse, to drive and back and no blown fuse. Not sue if that part is pad or just a short in one of the wires that goes to it!!!???!!! Still running rich and crappy btw when cold. I packed it all up and will go back tomorrow and see if I can find anything else out and start cleaning up all the ground connections. Seems that I have a couple of issues running simultaneously.. What a mess, any suggestions would be appreciated. I need to get my hands on some wiring diagrams for the auto park system and all the wiring. On a good note, the springs are great, brought my front end back up to the height it was supposed to be at with out the air bags and the ride is great. I will probably not figure this out tomorrow and will probably have to wait until the weekend. Good time to trade her in for newer model!

[Tommy_U]

The ign fuse on my coach was down under the dash near my left foot. I have a drivers door so I as able to get to it pretty easy. It also concerns me that I do not know why it blew. I did notice that the auto park light and check engine light are all powered by the ign circuit. I can remember a few times when I put my coach in park that the engine died but it has always started back up no problem with no blown fuse. I wonder if the switch on the column for the auto park is going bad. Something I will have to investigate. I never found a 20 amp fuse either but there is a mess of mires under the dash and 2 relays sitting on top of where the steering wheel column connects to the coach. The 8ish volts I was getting was on the wire that runs to the sending unit. I am trying to find out if that wire should have any voltage and if so how much. My gas gauge reads full so I suspect there might just be a bad ground. I am going to test the gauge while I have the dash apart. Thanks for the link.

[More_To_See]

Great. Good job. Where did you find that Ign fuse on your rig. I'm going to have to find where my Ign power for the fuel pump power is picked off from. My wiring does not correspond to what I see on my Winny. I never found a 20 amp fuse for the fuel pump.

Where is that 8 volts you mentioned?? All voltages for the fuel pump should be 12 volts. That pump draws a bit of power. Measuring back near the pump somehow might show less than 12 volts due to loss in the wiring but 8 V would seem way to low to me. In fact you should have a full 12 V at both the relay and oil sending unit I'm pretty sure. I'd be concerned about any (or much) less than that when the pump is running.

Here is some theory about how GM Fuel Gauges work. I hope this is true for their trucks (P30s) too. I'll have to dig out my manuals tomorrow and take a look at what they way.

Also, I'd be a little interested as to why that fuse blew. Maybe look around a bit or grab some harnesses and move them around a little.

Regards, M T S

[Tommy_U]

After checking fuel pump relay and oil switch I found that I had blow an ignition fuse. Once it was replaced I had fuel pump and it started then died. Did that about 3 times then stayed on. Seemed to not be running quite rite then after warming up a bit it was much better. It did stall one time when I put it in reverse. The check engine light was not working because of the blown fuse as well. Still having a problem with the gas gauge reading full when I know it is close to empty. I did test the wire going to the sending unit and it has a little over 8 volts. Anybody know how many volts it should have? Sunday I will finish putting everything back together and take it for a little drive. Thanks guys for all your input it really help me having a list of things to test.

[Tommy_U]

just a quick update: I stopped at lunch at the local GM dealer and had them pull the part # for the fuel pump relay. The relay I have pulled out cross references with the replacement part # and is used for many applications so there is a very good chance that I actually have found the correct relay, will know tomorrow. They ran my vin and even thought the letter represents a 96 it comes up as a 94 chassis so at least I know if I need to use the vin at any time for ordering parts the vin # is ok.

[Tommy_U]

Yep, that is what I am going to do. I was on the phone with Fleetwood and GM. GM gave me what appears to be some useless websites to visit. I found out I have a Vin# that says it is a 1996 which is impossible cause my coach was manufactured in 4 of 94! lol The vin # must have been taken from the frame wrong or something. I was looking through the Chevy service manual I have and found the diagram I had seen on line that showed the 2 relays and it was pre 1990. I will post any finding after my testing out on Saturday and Sunday

[turbojimmy]

That sounds like the correct relay. I'd put 12V to that wire and see if the pump runs.

[Tommy_U]

thanks more_to_see. I am compiling all this information and have tried to locate the relay. I found only 1 relay on the dog house near the gas peddle on the inside but believe it is A.I.R Converter Module assembly has 14103304 on the top of it but not positive. I have seen 1 diagram that shows the AIR and the fuel pump relay both mounted on the side wall of the dog house and then saw another with only the fuel pump relay so I am not certain if this is the fuel pump relay or not. It does have five pins and has a red wire not connected to anything leading me to believe this is bypass test wire. Do you or anybody know the part # for the fuel pump relay? I was at my dads tonight looking at his 92 bounder on a P30 and the engine would run with this same relay unplugged. Would not start if both the relay and oil sensor was unplugged. Engine would start if it was plugged in and Oil sensor unplugged. I could hear the fuel pump when the key was turned on weather this relay was plugged in or not which leads me to believe this is not the fuel pump relay or it has been bypassed. Also the engine stayed running for over a min with the oil sensor unplugged. It made no sense cause the engine should have not kept running with the oil sensor unplugged so this did not help me one bit. On a side note it seemed as if the past owner of the Bounder had bypassed the something and ran the fuel pump where it did not need the oil switch and possibly the relay????!!!!! Forget the Bounder need to stay focused on the Southwind! lol BTW before I stopped at my dad I was looking for the relay on the southwind and turned on the ignitions and noticed all the gauges work the parking brake light is on but no check engine light! Any other input is appreciated.

[turbojimmy]

Sully2 wrote:
The normal engine mounted pump cant "suck" gasoline the distance it needs to go...hence the AUX pump inside the tank....to help with that problem an it runs as long as the engine is running

Yes it can. The engine-mounted mechanical fuel pump is perfectly capable of feeding the 454 on the longest of gas RVs. Mine does just fine on my Allegro M31. The trouble arises in a couple of areas that are moot for this discussion but I'll point them out anyway.

1) Vapor lock. Fuel boils in the line from the pump to the carb. The external fuel pump was installed from 1985 1/2 and up to help pressurize the system to avoid this problem.

2) Inoperative external fuel pump. The mechanical pump can't suck through a failed or inoperative fuel pump as well as if the path were unobstructed. It will work under most conditions, but will be prone to vapor lock more so than if the failed pump weren't in the path.

By 1993, however, an in-tank pump was used. It provides the higher pressure needed for the fuel injection and is not generally prone to the vapor lock issues suffered by the carb'd configuration.