Calling all fuel injection gurus

[87Lowrider]

OK... I've got a very annoying fuel pump fuse blowing issue.

Some say it's overheating since I am regulating the pressure down to 4 or 5 psi. I don't disagree but I'm not ruling out a broken wire maybe shorting out somewhere in the harness. The problem is intermittent at best but happens at the worst possible time like yesterday in the middle of an intersection. I changed the fuse in the intersection before the light changed... (I'M SO FAST, I CAN TURN OUT THE LIGHT AND JUMP IN THE BED BEFORE THE ROOM GETS DARK) hehe.

Anyway, 1987, as you know was the first year for TBI and the harness and computer are still in place. I just have it tucked behind the engine. I'm considering updating the 1976 454 that's in the truck now with EFI.

Anyone done it? What kinda issues can I expect? This will be my winter project, I'm sure... (after Dec 13th when my little girl walks down the isle)

Thanks!

Kenny

[Albatrossian]

Ken.. alot of the aftermarket FI systems now are pretty much plug 'n play and you can tune them with a laptop. I have worked with some supercharged Mustangs with the FAST system and it's really easy to tune with ALOT of tweakable settings. I know you'll do your research, but I've never heard a bad word about any of the systems out there.

[texassquarebodies]

Tbi is the way to go! You will need a 454 computer, tbi intake, throttle body-they have 2" holes in them versus a 350 has 1 11/16 holes, also has bigger injectors, also all that wiring next to the tbi , map sensor and all that good stuff. I believe a 454 tbi plugs are a little different than a 350. A website called turbocity.com has a lot of parts to make this swap work. Good luck !

[lolife99]

Why not eliminate the factory "in tank" fuel pump and install a hi perf mechanical fuel pump on the engine for now?

[spudz]

I agree.... just make the factory sending unit a pickup by removing the fuel pump and installing fuel hose where it used to be.. then, terminate the power to the pump.. then install a manual pump.. IT WILL be MORE then enough for you and less troublesome... and a cheaper fix..

[87Lowrider]

Originally Posted by lolife99

Why not eliminate the factory "in tank" fuel pump and install a hi perf mechanical fuel pump on the engine for now?

Originally Posted by spudz

I agree.... just make the factory sending unit a pickup by removing the fuel pump and installing fuel hose where it used to be.. then, terminate the power to the pump.. then install a manual pump.. IT WILL be MORE then enough for you and less troublesome... and a cheaper fix..

I considered that initially.... but elected to go with the factory intank pump because I didn't know what to do about the factory fuel lines...

I didn't think I'd run into this problem when I installed the BBC. I'm only assuming that the pump is actually overheating because I'm regulating the pressure, heating up the pump in the process and blowing ECM2 fuse in the process. I'm also planning on a EFI conversion over the winter so I want the electronic pump in place unless I can to it with mechanical.



In the diagram above, anyone know where the Fuel Module is on the truck? Could it cause the ECM2 fuse to blow intermittently?

I was considering picking up a new fuel pump relay and fuel module today just to eliminate pieces of the puzzle.

Thanks for the help!!! - By the way... I'm in the chat room every night if anyone wants to sign in.. some pretty good conversations going on in there quite often.

Ken

[87 STEPPER]

Originally Posted by 87Lowrider

In the diagram above, anyone know where the Fuel Module is on the truck? Could it cause the ECM2 fuse to blow intermittently?





Ken

Ken unless you or someone else added it your truck dosent have that fuel module your truck was orignally a 5.7 and it's not over 8500GVW.

I also think you have the fuel pump power grounding out somewhere thats about the only way it will blow the fuse.

An overheating pump wouldnt do it cuz if it overheated to the point to blow the fuse then when you replaced it. it would blow right away cuz the pump couldnt cool off the fast. cuz your so fast at replacing it

[87Lowrider]

Bruce,

Thanks for the reassurance.

I think your right on the fuse issue... my wife reminded me that this seemed to start after I put in the Dakota Digital cluster.. I'm wonderin' now if there's not a wire behind it that is exposed causing this problem?

I'm hoping to get into it tonight to see if I can track it down.

Thanks!

Kenny

[87Lowrider]

Originally Posted by 87 STEPPER

I also think you have the fuel pump power grounding out somewhere thats about the only way it will blow the fuse.

An overheating pump wouldnt do it cuz if it overheated to the point to blow the fuse then when you replaced it. it would blow right away cuz the pump couldnt cool off the fast. cuz your so fast at replacing it

Originally Posted by Captkaos

Kenny, You got a bad ground somewhere. The ECM2 lead should be pink/black.
Are you using nothing from the ECM except the fuel pump?

I took the truck out this morning and blew 3 fuses in a matter of 2 blocks. A direct ground somethere!

YOU GUYS WERE RIGHT! (and I am that fast)

This afternoon, I crawled up in there and got cozy with the engine and found a connector touching the firewall / block from the tbi harness. I missed it the other day. A little Elec tape and presto. I drove it around for about an hour this afternoon, starting and stopping, etc.. so far so good.

Thanks Again for your help!


Kenny

[87Lowrider]

Well,

I drove the truck to work today. Took it on several service calls to customers sites... started and stopped several dozen times... no blown fuses!!!

Still nervous about it though... hopefully I've got it licked!

Kenny

[Albatrossian]

If your truck originally came with a 305 and a single tank, it might not have one.

[87Lowrider]

It's an original 5.7L w/dual tanks... the pass side tank has been removed previously.. I'll add it again soon though

[Albatrossian]

Hmm.. I dunno dude. All that new-fangled fuel injection crap! Give me a carb or give me death!

[Captkaos]

Is it blowing the Fuel pump fuse or the ECM fuse?
Are you still controlling the Fuel pump with the ECM? and none of the sensors are connected?

Check to see if the Injector harness is grounding on something. I would think Somewhere you have a ground.

TBI would be the simplest. (probably easier than the Carb setup) 454SS trucks were the only setup that got the larger 2" TBI, the rest were the same unit. If you really want a 2" TBI, buy a Holley.
The rest is just a matter of hooking all of your lines/sensors back up that came off the Existing TBI and changing out the chip.

[87Lowrider]

Originally Posted by Captkaos

Is it blowing the Fuel pump fuse or the ECM fuse?

Chris,

It's blowing the ECM2 fuse. Intermittently during the drive but now everytime I drive it. A couple days ago when I drove it last, I drove it 40 miles with no problem, parked it for oh 3 hrs or so, drove 5 minutes and it blew the fuse in the middle of an intersection on me. Sounds like a short to me?

Yes, I have everything unplugged since I'm using an Air-Gap intake and a EDL 750.

Kenny

[Captkaos]

Kenny, You got a bad ground somewhere. The ECM2 lead should be pink/black.
Are you using nothing from the ECM except the fuel pump?

[454HO]

Kenny,

The ECM only turns on the fuel pump relay for a few seconds when you first turn on the key. This is only to prime the fuel line and provide fuel pressure for start up. Once the engine starts, the oil pressure switch is what is powering the fuel pump circuit. Do you still have the oil pressure switch hooked up? Is the fuse that is blowing the 10A ECM_B fuse shown on this diagram?

As for going fuel injection, the factory 454 TBI system is barely good enough for a 260HP stock motor. I think you have a pretty healthy cam, and are probably about double that horsepower. So I would be looking for a multi-port injection setup. You can get an intake manifold and fuel rails from Edelbrock and an aftermarket ECM from someplace like FAST. Then all you need to do is build the wire harness.

[87Lowrider]

Originally Posted by 454HO

Kenny,

The ECM only turns on the fuel pump relay for a few seconds when you first turn on the key. This is only to prime the fuel line and provide fuel pressure for start up. Once the engine starts, the oil pressure switch is what is powering the fuel pump circuit. Do you still have the oil pressure switch hooked up? Is the fuse that is blowing the 10A ECM_B fuse shown on this diagram?

As for going fuel injection, the factory 454 TBI system is barely good enough for a 260HP stock motor. I think you have a pretty healthy cam, and are probably about double that horsepower. So I would be looking for a multi-port injection setup. You can get an intake manifold and fuel rails from Edelbrock and an aftermarket ECM from someplace like FAST. Then all you need to do is build the wire harness.

Yes... the switch is hooked up on the left side of the block along with a sender for the DD dash. Yes, that's the fuse that is blowing.

All I have to do is build the harness - haaaa you make it sound easy!!! lol


Kenny

[87Lowrider]

Originally Posted by Captkaos

Kenny, You got a bad ground somewhere. The ECM2 lead should be pink/black.
Are you using nothing from the ECM except the fuel pump?

You're probably right! From what I know... wiring is stock. So, I don't think anything else is on ECM2.

I started from the bottom up and was reading Gregs reply and didn't answer yours.

I'll check my grounds!

Thanks!

Kenny

[74 C-30]

is there any simple way you can just run the pump without the ecm? like an ignition hot fused wire straight to the pump? or is some kind of controller needed?

[87Lowrider]

I didn't have any time to work on the truck last week, but I did get on it this weekend.

I replaced the Fuel pump relay and the oil pressue switch just for good measure. But, I think the culprit was a ground wire on the harness that normally connects directly to the block. I had it connected to the firewall. The mounting screw was stipped and loose. Plus the connector was screwed against a painted surface... not a good ground anyway.

I moved the ground wire to a location on the block with another ground wire, fixed a couple loose-ends and spent some time driving around town over about an hour or so. No fuses blown yet..

I'm going to drive it around next week to see if it's stable enough to take to Jackson TN on Nov 1st for the board meet there.

Thanks for all the help guys!


Kenny

[87Lowrider]

Three days now without any blown fuses in the ECM2 circuit.

And then, wham!

I was driving down the road today and it blew and the motor fizzled out. So, I pulled over, checked the fuse, sure enough, it had blown. WHY??????

I've had all I can take... I've checked all the wires in the harness, nothing shorting out that I can see and good grounds.

I have a nice Mechanical Holley Fuel Pump. I'm going to install it this week and re-route my fuel lines to it and to the Carb.

A Question comes to mind... Since there are 2 lines coming from the tank, can I plug the line coming from the electric pump, pull the fuse for it and connect the mechanical pump to the return line and let it suck the fuel from the tank?? I don't think the mechanical pump will pull fuel through the electrical pump, right?


Kenny

[andresco50]

Is easy today you only need few things you have kits with all the stuff.... I love my rochester

[Pyrotechnic]

Are you using a returnless regulator ? This will really load down the pump. I would recommend switching to a bypass style regulator that has a fuel return outlet and will bleed off the excess pressure to the tank. Your return line should already be there so the plumbing shouldn't be that bad.

http://store.summitracing.com/partde...5&autoview=sku

Don't know about using the return line for a supply. It may not have a sump down to the bottom of the tank like the actual supply line does.

However if you know you are going to aftermarket EFI and a high pressure external pump (your current in tank pump will not cut it for multi port EFI) then it may be best just go to the parts store and buy a new sending/sump unit for a carburetor application and be done with it rather than spend money on a new regulator.

[Captkaos]

Kenny,
I am with Pyro, drop the tank and install a non-efi sending unit, reconnect the fuel/vent line and run your mechanical pump.