LOOONG Weekend! Goodbye carb hello EFI!

[AJII]

Let's see...started Friday night about 8pm and finished up Monday Morning about 4am.

Things completed:

• Hydroboost Conversion. Had to changed the pedal as well. And the lines 'almost' fit. So needless to say this took quite a while.
• Changed out the rear springs to Tuff Country EZ Rides. The stock ones wwere beat. Bolts on the hanger were completed rusted together. Another fun job.
• Removed both gas tanks and installed 87 sending units and high pressure fuel pumps. Also ran all new high pressure hose from tanks to selector valve.
• Rewired the fuel system components to power the in tank pumps. VERY confusing since between 85&87 Chevy decided it would be a great idea to change all the wire colors.
• Mounted and plumbed the fuel lines for the EFI. Corvette regulator and braided line.
• Removed the carb setup components and put on all the EFI stuff. The wirng harness I modified actually WORKED!!!!!!

So yah, it was a long weekend, but made alot of progress!!

Friday Night

1985 K10 Carbed 5.3 Swap - YouTube

Sunday Night

1985 K10 5.3 Fuel Injection First Start - YouTube

[chebyshortbox65]

Better check your fuel pressure at the fuel rail when I ran through the tank selector valve it pushed my tail pressure in excess of 100 psi.
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[AJII]

I'll do that! Thanks for the suggestion.

Did you find out what was causing it? Selector valve not letting the return flow well enough and pushing through the regulator creating excess pressure?
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[piecesparts]

Please describe to me, your fuel pump setup. You have two fuel tanks with electric pumps in each? If so, then how are you controlling them? I thought the 87s had only one tank. I am interseted as I have an 84, that I would like to upgrade.

[gchemist]

You can buy pumps that fit stock gas tank. Follow this 77 LS conversion.

http://www.hotrodlane.cc/77chevytruck/77chevy.htm

[DirtyLarry]

Originally Posted by AJII

I'll do that! Thanks for the suggestion.

Did you find out what was causing it? Selector valve not letting the return flow well enough and pushing through the regulator creating excess pressure?
Posted via Mobile Device

Nice work AJII! I kinda wondered why you had a carburetor on an LS engine in the first place.

I agree with chebyshortbox, the stock Pollock dual tank switch valve only has a 5/16 return port, which I found to be too restrictive causing the head pressure to sky rocket up near 100 PSI like he mentioned and I could not find any other switch valves on the market with a bigger return port. If you think about it, fuel pressure is regulated on the return side anyway. If there is a restriction on the return line anywhere, the supply line pressure goes up. An actual pressure regulator is just a controlled restriction while a tiny return line through the switch valve is too much restriction. I have no idea how Hotrod lane pulled off using a stock switch valve. I even called the supplier Pollock and they did not recommend using their dual tank valves for higher pressures above TBI type pressure (12 PSI).

On my truck I have an EP381 fuel pump in the LH tank then use a center mounted diesel transfer pump to move fuel from the RH tank to the LH tank for fill-ups on the fly. Same operation the diesel guys use with their big auxiliary bed mounted diesel tanks. Thinking of changing the center mounted transfer pump to low pressure in tank TBI fuel pump this summer though just to speed up the transfer process. I do not use the dual tank switch valve for anything other than sweeping back and forth to check tank levels (no fuel lines are going to my switch valve at all).

[Skunksmash]

Also a lot of people have problems with their AC switch killing the truck when they slow down and turn in somewhere. Its cause in the newer trucks the selector unit in the dash shuts the AC off for the turn. The older trucks don't have it, and it kills the truck. People wonder why their truck is always just dying at random. Well its not random its when you slow down and turn.

[AJII]

Does the selector valve add additional restriction? Because from the factory, trucks with LS motors have 3/8 feed and 5/16 return. So the line size should be just fine.

I'll check the fuel pressure and see what I've got. You guys have me worried now. haha. I read through Glock's thread about his swap, and he never mentioned anything about excess pressure, so it's something I hadn't thought about.

That's a good idea about the transfer pump. How do you have it plumbed?


Edit: Just saw your comment about Pollak's response...says right on the selector valve max PSI of 65.

[Hoods69BadBowTie]

Sweet good job on the swap. Looks great and sounds good as well. Now go out and put some miles on it and test it all out haha

[DirtyLarry]

Originally Posted by AJII

Does the selector valve add additional restriction? Because from the factory, trucks with LS motors have 3/8 feed and 5/16 return. So the line size should be just fine.

I'll check the fuel pressure and see what I've got. You guys have me worried now. haha. I read through Glock's thread about his swap, and he never mentioned anything about excess pressure, so it's something I hadn't thought about.

That's a good idea about the transfer pump. How do you have it plumbed?


Edit: Just saw your comment about Pollak's response...says right on the selector valve max PSI of 65.

Nah, I don’t believe the switch valve itself causes restriction…just the small return line cases restriction for some of us. In your case, being you have a 5/16 return line on the engine you should be in good shape. The 8.1L uses a 3/8 return and didn’t like the small ports in the switch valve. I got a new valve from the local GM dealer for a 1990 V3500 and it isn’t marked in anyway with PSI, it only has the suppliers name marked on it. After chasing high pressure issues I disconnected the return line at the valve and ran it straight into a bucket which allowed the fuel pressure to run normal. At that point is when I researched valve options then called Pollak and they said no go on anything higher than 12 PSI. Odd, 4 years later, their website now says 65 psi. Maybe, I am losing my marbles or something.

None the less, sounds like you are in good shape with the return line size!

As far as my Aux tank, the fuel gets sucked out by way of a 6.5L diesel lift pump then dumps into the LH tank through a fitting I put in the top of the sending unit.