Need help with the In-Tank pump, FOUND SCHEMATIC OL

[D_E_Bishop]

I have written about the starve out problems I've been having with the 1989 Chevy naturedly aspirated 454 in our rig. I had it to a shop to repair what needed repairing so I would pass smog here in CA. I have been to four shop since it pasted smog but still won't climb hills and asked each shop to check the in-tank pump pressure on the output side of the regulator. None of the shops checked, all said it was an electrical problem.

Today I bought a very good pressure gauge, 20 feet of gas hose and the fittings to install the gauge and hook up to the regulator. Zero pressure. The regulator is not the problem. There is free flow through the regulator, there just isn't any pressure.

I would like to verify that there is power to the pump but don't have my factory schematics, they are in the garage along with 3/4 of our belongings due to a remodel and complete interior paint. Our kids and grandkids moved most of our stuff and it is all mixed up and I'm not sure where anything is.

Does anyone have a full set of wiring schematics for a 1995 Bounder? Or can anyone tell me exactly where and what color the wires are up in the cockpit? I didn't have a full set of attachments for my DMM so I couldn't check voltages accurately at the disconnect by the tank. I'm going back out tomorrow and try again but a schematic would sure help.

We are leaving Monday for a little road trip and I'm not looking forward to the motels.

TIA

Found not only the schematic but a description of the entire oil pressure interlock system and why pressure builds up in the fuel tank.. There is a lot of other things I figured out after reading some stuff on Google and now I know that the pump is working and that the relay interlock is bad.

[MEXICOWANDERER]

MANY of the GMs had a tank electric fuel pump to AID the engine mechanical fuel pump. You rig up a thirty-foot suction line to a mechanical fuel pump and on a hot day you will get a vertical learning curve lesson about vapor lock.

[eHoefler]

I had a 89 suburban with a very similar problem, it turned out to be the ignition module in the distributer. It sends a signal to the computer, telling it that it is running and sends a signal to the fuel pump.

[D_E_Bishop]

Here is the site address, actually it is the query answer page.

https://www.google.com/?gws_rd=ssl#q=1989+P30+Fuel+pump+relay+location

There is also a IRV2 thread just a couple of answers lower on the list with good info.

[D_E_Bishop]

This is what I know so far,a 1989 P30 has an in-tank, I do not have access to the repair manual and the OEM number. Pumps for Chevys of that vintage have an out put pressure of 12 to 30 pounds. According to the speed shop where I bought the regulator and a whole bunch of mechanics, the delivery pressure to the on the block fuel pump is 4.5 to 5psi. I have set mine as close to 4.7 as possible.

I have located six or seven pumps that look like mine does(Isaw the old pump, not the entire assembly)that are for Chevy's of that era but not the specific pump and associated specifications.

As far as testing the pressure before the regulator, I would only learn what the pump output pressure. Now that I have the delivered pressure set all I am concerned with is, does the carb get that pressure when I am going up hill with the pedal to the metal and the secondary's open.

I found the fuel pump relay thanks to Mexicowanderer and a graphic I located by Googleing, "1989 Chevy P30 Fuel Pump Relay location" Google not Yahoo or Chrome.

I removed the relay and disconnected it from it's five conductor plug and cleaned the contacts and opened the relay housing to watch the operation of the relay. According to the schematic and written description, when the ignition key is turned on, the pump will run to build up pressure in the float chamber, you then depress the throttle, "ONCE" and release. Then you turn the key to start and the power to the pump is interrupted to prevent flooding of the carb. When the engine starts, and builds up oil pressure, the relay holding voltage is supplied through the oil pressure switch.

I watched my relay and it operated normally. I was able to watch the fuel pressure on the gauge. I bought 20 feet of hose to enable me to have the gauge in the cockpit when I was at the wheel.

Now here is what I am guessing about but education, experience and common sense make me 85 to 95% sure I know what I am talking about. I had several things to do before I could do a test run, you have to know that all this is taking place in my storage yard and I have to be very neat and orderly and not spill anything on the asphalt. Because I needed to run the engine in my Sidekick. Wash the window of the sidekick so I could put the solar battery minder in it, clean the windshield of the MoHo and juggle three vehicle in and out of parking so as not to block any other renters parking spaces.

All told it took about an hour with the engine running and the temperature gauge was at the high end of it's normal range. As I drove up to the exit gate and started out I noticed the pressure gauge was reading "ZERO". I pulled out, turned around and went back to my space, opened the doghouse removed the relay cover and the relay was no longer actuated.

The relay was very hot and when I could get it up on the cover on the floor the coil read "0" ohms. I think that the coil is bad, both ends are a somewhat darker color rather than the lacquered color of a copper wire while the center of the coil looks normal.

This would account for the engine running very strong when we first start off but start to starve out after about ten to twenty minutes later. Even my wife picked up on that.

The answer to the question about the gauge is; I forgot the name of the manufacturer, it is American made and measures from 0 to 15 psi. It is oil filled for a couple of reasons, the most important to provide dampening of the vibration often found in race cars. It cost about $35. As I said earlier, I bought the Holley regulator when the original Holley part failed and was leaking all over my SIL's parking area. Both the regulator and the gauge were purchased from a very highly respected speed shop in Pasadena, CA by the name of Blair's Speed Shop. [COLOR=]The Holley regulator is not a tee with a restrictor, it is a diaphragm regulator just like a propane regulator. The pressure is critical in race engines.

The staff at Blair's also offered some what to do's if the relay was good including to make sure the return line was functioning. Because I have been there off and on since I was 16 they are nice to me.

Thanks to j-d for the picture. We also have several resident bob cats in that area and at least two within 200 yards of our house.

If I forgot to mention it earlier I have the stock Quadrajet carb.

If I failed to mention anything other than the site where I got the graphic and schematics, it is because I have to Google it and wanted to get this out first. I'll post it later.

Thanks to all and when I pick up the relay and do a test run I repost and tell about it. I may not get out to storage until next weekend because we're off up the coast to find some cool if possible and good calamari steaks if nothing else.

Dave

[turbojimmy]

1989 should be TBI. 9-13 PSI fuel pressure. But, again, need to check with the engine running. Pump will only run while cranking, and if there is oil pressure (that is with the engine running).

[j-d]

I'm sure I'm not the only one who'd like to see the information you found. Please link it, post it, whatever. Would like to see that Regulator, too.

I asked about the gauge you bought because I wanted to know if it was for Carbureted or EFI. Carbureted probably calls for 5-to-7-PSI at the carburetor. My EFI fuel pressure gauge reads 0-to-100-PSI and 5-PSI would barely move the needle to the first tick mark.

[eHoefler]

You need to check fuel pressure on the supply side of the regulator, not the return side. On the return side you have nothing to restrict it to build pressure, it is open to the tank for return. The regulator is what causes/makes the fuel pump build pressure. You need to connect your gauge to the carburetor/fuel injector side of the regulator.

[j-d]

Eagle Rock



Wow!

And yes, I saw the Deer.

Say you've got In-Tank Electric Pump ACDelco EP386. What is its Output Pressure, going into that Regulator (which I can't find so far)? Our 460 Ford, about the same vintage, had an electric in-tank pump with a return line back to the tank. There was no mechanical pump on the engine. The "regulator" was nothing but a tee with an orifice in it. The idea was to provide the fuel the carb demanded while maintaining a flow that prevented vapor lock. I never cut one apart to see how it was made, but I heard of them failing in a way that they sent all the fuel back down the return line, starving the carb.

[turbojimmy]

You state that it's dying on hills. If it runs at all, it's not likely the fuel pump. If you really had 0 pressure on the output side of the regulator, it would not run at all. You have to measure pressure with the engine running (ideally when it's misbehaving), or during the three-second or so fuel pump prime when you turn the key on.

Need more symptoms for a guess at the cause. When you say it won't climb hills, what's it doing? Just no power? Any backfiring or sputtering?

[j-d]

Please list the Make/Model of the Pressure Gauge, or even a picture of its Face.

Please also clarify it's the 1989 carbed chassis you're working on. You ask for a wiring diagram 199-FIVE Bounder. Did you mean 1990? For that, I'd try a separate thread in Class A.

Also, what's the chassis model designation? I wanted to look at fuel pump etc. on RockAuto and found P20, P30, P40. Hadn't heard of P40, looked at P30 with 454.

One in-tank pump, only? The RockAuto page shows mechanical engine-mounted pumps.

I'm told the 454 needs 25-GPH on a full power climb.

[wcjeep]

Not familiar with your setup. Relay's do go bad. Check that first.

[MEXICOWANDERER]

Power goes through the wire that will make a test light glow with the igntion switch turned on. The test light will play possum when the Fuel Pump fuse is pulled. The pump most likely has a relay so underdash work may not be fruitful.