Does anybody know for certain if the 87 Formula (LG4) really has an electric fuel pump in the tank?

 

Both of mine do. Don't know for certain yours does.

They'll be a two-wire oil pressure switch installed rear of block near distributor. Tee'd off the fitting for the single-wire oil pressure guage.

 

OK. The LG4 is long gone, but the Goodwrench 350 is correctly installed and all stock "stuff" was put back on when I swapped it. Looks factory except for the air cleaner, so there is a tee behind the distro with the o/p sending unit on one side and a plug on the other so I guess that means this car has the aux pump in the tank. Naf, have you ever had one of those electric fuel pumps go bad? Also have you ever been able to hear it when the car is running?

 

I tested mine once by jumping the relay with the supply line to the mechanical pump disconnected. Made sure it flowed fuel. Don't think I've ever heard it run.

I've read posts here claiming they're prone to failure but never read any that relayed that from personal experience.

 

It's a bit cool (28f) in central ohio this time of year and my garage is not heated so I probably won't be testing it till it gets a bit warmer. I am just wondering what affect the aux elec f/p would have on fuel delivery. The car was running excellent and I pulled in for fuel, shut it off, and then bam. Would not start right back up, checked on the spot and there was hardly any fuel squirting in. Made it home, (barley, stalling and backfiring indicating a super lean condition) changed the fuel filter but no change. Funny thing is, it didn't throw any codes. I have also suspected maybe the knock sensor failed and is pulling out timing, maybe. But again, no codes. Thanks for imparting your knowledge Naf, it was helpful.

 

In case anyone is wondering I am running a Goodwrench 350 (4 bolt, cast crank and slugs) with World Product S/R Torquer cast iron heads (2.02/160, 170cc intake runners, 67cc c/c), Comp Cams roller tip 1.6 rockers with Crane kool nuts, Crane chromemoly pushrods, Edelbrock Performer EGR intake, the stock Q-Jet (Rebuilt and Slightly Modified by me), Accel Billitech Distributor, Accel coil, MSD 6, MSD 8.8 wires, Lunatti 06103 cam and lifters (.442/471@1.6 204/214@.050) Edelbrock double roller timing chain, Melling HV55 oil pump, Carter 80gph fuel pump, Edelbrock tubular exhaust, Dynomax ultraflow catback and AC Delco rt44 plugs. Stock 700 tranny, and stock 9 bolt with 2:77. Car runs great, (no check engine light unless there is a problem) all 100% legal and gets 24mpg highway at 70 on cruise with a/c on. All put together by myself and my wife. It's her car.

 

Personally, I've never had a 3rd gen with in-tank electric pump, but I've heard of several failures of that piece on this Board.

For what that's worth.

 

there is a test point on the aldl connector but I cant remember if it tests the relay output or what but on my 90 there is an in tank pump and when it is on I can definatly hear it running..are you using a bypass regulator or something like that?

 

Five7kid, thanks for looking in, your comments are accurate and anything you have to offer is greatly apreciated on this end. Buzzman, I am not aware that carburetors were offered on any third gen after 87. I am just out of sorts on WHY an electric fuel pump was used with the mechanical fuel pump. This is proving to be somewhat mysterious as to why GM would do such a thing. I guess what I am after is, can I modify my fuel tank pick-up, eliminate the electric f/p and still provide enough fuel to the engine. I don't see why not. I am going to do this and will keep all of you up to date. It just won't be done for a few weeks from now. As I stated earlier, this car ran fantastic as a daily driver for two plus years after I installed the previous mentioned engine and I just can't seem to find the issue here. Everyone's suggestions and info are appreciated. Maybe I will try and locate a fuel pick-up from a non electric f/p car and see how that works. Stay tuned.

 

They did it as a remedy for vapor lock, a common complaint with earlier years. There was a dealer-installed kit which included an in-tank electric if people complained about vapor lock while under warranty. They just made it standard in '87.

Another reason is by '87, they were going EFI in everything else, so they just went ahead and put them in the carb cars as well. I interviewed with GM in '85, after the '86's were out, and they said they'd made their last carbs. Well, that wasn't quite true then, but it was by the next year.

 

mine had tbi from the factory not carb..I just converted it

 

my 87' used-to-be lg4 car has the in-tank pump, my new engine has no mech fuel pump hole (as it was supposed to) but i shorted that switch on the oil press and i could here it pump, so i know the pump is good, so i installed an in-line 6-7psi pump and have had no fuel starvation issues (though its not a monster or anything (lo5 i think?) but i was told that if the in-tank pump did not work the in-line pump would not pull enough fuel. *but* i have never heard the pump from inside the car.

.02

 

So, the in-tank pump is in fine working order. I shorted the switch and pumped out two and half gallons. I figured that maybe the pump was working at start up and would quit after a few minutes. Doesn't seem to be the case. Replaced the carter mechanical with another carter, still runs for a few minutes then just stalls out. I don't think it's a timing issue, the Accel coil & bilitech distro are pretty new........hmmmm

 

Fuel, air or spark. What's it missing when it refuses to restart?

Could be a restriction in the fuel line or filter. Pull the line off at the carb and check flow and pressure with it running. It will idle for a minute or so on the fuel in the bowl.

No other changes to the fuel line routing or anything?

 

when I first converted mine the fuel pump only ran for like 3 seconds...the fix is to run a constant on 12v source to the pump relay so it runs all the time when ignition is on...Im out of town but when I get back I can verify the color of the wire at the relay.

Buzzman1

 

I presume that's not the case from what he posted above, but the ECM will override the OPS for initial start up. If the OPS or its circuit is bad the fuel pump will cut off after the car is started AND the carb will starve for fuel after a few minutes.

Easy enough to check. Start and run the engine with the fuel pump relay jumped.

 

Thanks naf, I hadn't thought of running the car with the in-tank jumpered. I'll try that tomorrow. Been busy helping my nephew with his 88 Formula 305 tpi. Thanks.

 

Ever get this figured out? I am having intermittent power loss issues on my 87 305 and am trying to figure out if i have to drop the tank.

 

GtoRockz, I did get this figured out. I thought I had wrapped up this thread. Oh well. I was running an MSD 6 on this car, and after all of the trouble shooting and work I put into this issue, it turns out the MSD box was malfunctioning.

So, when does your car experience the power loss?

Can you elaborate a little?

What mods if any have been done to your car?

 

Thanks for the quick reply csmith3. This is an 87 305 carb model completely stock with 52k original miles. The engine cuts out like it is starved for fuel, sometimes on the highway and other times when i put it to the floor, or sometimes when just cruising as 35mph. Engine does not shut off and usually i can baby it and it is ok. It has had a *major* service including mechanical fuel pump and recently changed the ignition coil and control module hoping that was it but the problem is still there.
The book says i have to drop the exhaust to get the tank out and it looks like a pretty big job to change the tank pump so was hoping to exhaust other possibilities before going that rout. There is a noticeable pressure release when i remove the gas cap.
The car normally runs and drives fantastic and i have put so much time, blood and sweat into this car already that i really thought all the hard work was behind me.. that is until i found out there is a pump in the tank. lol

 

Your car looks very nice, and she should as good as she looks!

Check the functionality of the in-tank aux pump before you drop the tank. You have to drop the rear axle as well! There is a connector on the oil presure switch behind the distro. The connector is about an inch and a half around. Remove the fuel line going into the mechanical pump, pull the connector from the o/p sending unit and use a piece of wire to just plug into the holes. If the in-tank pump is good it will start to flow immediately. Be sure to put some sort of catch can under the fuel line, don't want spilled fuel everywhere.

Has the fuel filter been addressed?

Has anyone fiddled with the carb?

Oh yeah, have you checked the egr valve or the egr valve solenoid? Those are known to go bad and can cause the type of condition you mention.

 

The fuel filter is new but have not checked the egr valve or the egr valve solenoid, not sure where the egr solenoid is located. The carb is un-touched with original adjustment caps still in place. The car threw a code for TPS and it is now currently unplugged and is running great without it. Was waiting for better weather to change it. When i first unplugged it the car was running so good i thought for sure it (TPS) was the cause of the cutting out but after about 150 miles it acted up again. Do these in tank pumps go in and out when they are going bad?
This has been going on for a few months and it seems if the in-tank pump was on its way out it would die at some point, or can these cars still run without it?

 

As far as the in-tank pumps go I have never had one go bad so I don't know what characteristics they will display. My experience shows that some e-pumps do go in and out and some die promptly. Hard to say. Just have to check it. I let mine pump out 2.5 gallons before I decided it was still pumping good.

Again as far as the car being able to run with a dead in-tank pump, I am not so sure. I don't think a stock mechanical pump can pull enough fuel past the dead electric pump to supply the engine with enough fuel to keep it happy. So my guess is no.

The egr valve solenoid is located on the passenger side near the rear of the engine. It has a hard plastic line going to the carb and another one going to the egr valve. When the car is not running the solenoid should be closed. This can be tested with a vacuum tester. (A great investment if you don't have one. It will serve you well with an older car like yours). The solenoid is controlled by the computer. In the old days the valve was controlled by ported vacuum on the carb.

Speaking of the carb, does it need rebuilt? The Q-Jet is a fine piece of workmanship and can provide a lifetime of use, and can be modified to feed high performance applications as well. But if it's 23 yrs old and only has 52k on it, that car has done some sitting around.

Check all the vacuum lines for leaks (again the vacuum tester is priceless), you are getting some codes with the TPS disconnected, but there may some other codes in there to help direct you toward wht the real problem is.

 

It will still try to run without it but will starve for fuel. Check it's operation.

Unplugging the TPS will cause the car to run full rich and screw up timing advance. Replacing it isn't that big a deal.

 

Thanks, i will do the test and check the other items you mentioned when it warms up a bit. My garage doesn't have a door an its pretty rough out there right now. lol.
I'll update when i figure something out.