Has anyone experienced this problem - The 1947 - Present Chevrolet & GMC Truck Message Board Network

greenhorn male · 12-31-2004, 02:35 AM

I have an 87 with a 305 TBI. It has dual tanks with the tank selector switch near the ashtray. On the toggle switch, up is the right tank and down is the left tank, and middle will kill the engine immediately. Just the other day after I filled the tanks, when I switch to the left tank the the engine still runs but with half the power and weak acceleration. When I switch to the right tank, it runs normal. Middle stills kills the engine. Any suggestions as where I should start to look for problems.

greenhorn male · 12-31-2004, 05:24 AM

Oops, I meant to post this i the message board. How do I transfer this there?

**smokinn** · 12-31-2004, 08:14 AM

Check your left tank sending unit could be plugged.

Jason

pastorjimk · 12-31-2004, 09:41 AM

Had the same problem on my 83...The rubber gas lines connecting to the top of the tank had become weak and were crimped. I had to drop the tank and replace the lines. While it's down you might as well clean out the tank

784X4GUY · 12-31-2004, 12:19 PM

Yeap I have this very same problem, gonna fix it here soon hopefully...Later Mike

greenhorn male · 12-31-2004, 03:20 PM

Sheeeesh! I just filled the tank with Chevron plus. Now I have to drop the tank to replace the hose. Do you know how heavy these tanks are full.

784X4GUY · 12-31-2004, 04:03 PM

Probably pretty damn heavy, Good luck. And don't drop it on yaself lol...Later Mike

chevymad · 01-01-2005, 04:31 PM

You say you have tbi? If so a cracked hose isnt the answer. It would just leak if the hose was cracked because each tank has a fuel pump inside. All lines are under pressure. You most likely have a fuel pump going out in that tank.

Russell · 01-01-2005, 04:45 PM

I'd second the weak fuel pump issue...

If you need a new used pump, I've got a spare one from a TBI suburban here. I am using the EFI tank to run my TPI, but had to replace the fuel pump with one from a Camaro, so I have a spare TBI pump

ElGracho · 01-01-2005, 05:09 PM

I have a TBI pump too, it's yours for the price of shipping. I'd also third the bad pump thought...

pastorjimk · 01-01-2005, 10:43 PM

Just for clarity...I didn't suggest a cracked hose, I said a crimped hose! You all may be right, just sharing my experience with the dual tank/dying engine experience...either way the tank must come down!!!

87 STEPPER · 01-01-2005, 11:11 PM

First thing id'e do is connect a high pressure gage 0-100psi and select the tank at fault and then turn the key on and pressurize the system and see if you have at least 35 psi if it's any less the problem could be a bad pump or the x-fer valve isn't making full travle and only opening part way.

This is a ruogh figure on the fuel weight useing 6.7 #'s for fuel density @ 60*F x's the gallons of the tank about 12 gal. i think and you have the weight= 80.5 Lb's

greenhorn male · 01-02-2005, 01:58 AM

Thanks for all the responses, advise and fuel pump offers. I'll try getting that pressure guage and test the pressure once the rain clears a little. I'll let you know if I need a fuel pump. Thanks again!

chevymad · 01-02-2005, 03:13 PM

Tbi fuel pressure is only 12-14psi.

greenhorn male · 01-02-2005, 04:21 PM

I was told 1987 is the first year TBI was introduced to pick-ups and this is the last year of this truck body style. I'd like to buy a repair manual like Chiltons but they might not cover it accurately because it is one of those transition years. I had this problem with a 1973 240z. What brand repair manual would you recommend.

Blue Beard · 01-02-2005, 04:41 PM

Make sure the switch is good, some of those broke or had wiring issues.

Switches are cheap...

SanitysBane · 01-02-2005, 05:17 PM

get a Helm manual,Click

1987SierraClassic · 01-05-2005, 06:32 PM

I agree with everyone else on the fuel pump issue. I had the same problem with a Ford truck. Either the pump is bad or the pickup tube is plugged. Either way you need to drop the tank.

I just replaced the tanks in my '87 and found that the easiest way is to remove them by unbolting the brackets from the frame and lowering them straight down. Don't even bother with the straps until the tank is out. The body shop snapped off the strap bolts and I ended up buying new brackets for $50 each. I replaced my 16 gallon tanks with 20 gallon and the only way we could get them back in was to put the brackets on the tank and then lift them into place (even with the bed removed). Luckily mine were near empty.

The fuel pump connections are on top of the frame rail just under the cab. Mine came apart really hard and I had the advantage of no bed at the time. I don't know if you can reach them without taking the bed off. I ended up having to cut the rubber lines and replace them. If you get new lines, make sure they are rated for fuel injection...some fuel line isn't.

Just thought I'd share my experience!

I have the factory manuals for '87 and they don't event mention TBI systems. The Chilton's book mentions it in passing. I found some good information on Chevy fuel injection in a book by Ben Watson "How to Repair and Modify Chevrolet Fuel Injection" ISBN 0-87938-502-2 The book gets into some good detail on how the systems work which is a huge help in diagnosing problems.

12-31-2004, 02:35 AM	#1
greenhorn male Senior Member Join Date: Jan 2003 Location: Bay Area, Northern California Posts: 1,344	Has anyone experienced this problem I have an 87 with a 305 TBI. It has dual tanks with the tank selector switch near the ashtray. On the toggle switch, up is the right tank and down is the left tank, and middle will kill the engine immediately. Just the other day after I filled the tanks, when I switch to the left tank the the engine still runs but with half the power and weak acceleration. When I switch to the right tank, it runs normal. Middle stills kills the engine. Any suggestions as where I should start to look for problems. __________________ 03 Tahoe 72 GMC Super Custom 2500 Custom Camper, my reliable workhorse. Dual gauged tanks, dual battery trays.

12-31-2004, 05:24 AM	#2
greenhorn male Senior Member Join Date: Jan 2003 Location: Bay Area, Northern California Posts: 1,344	Oops, I meant to post this i the message board. How do I transfer this there? __________________ 03 Tahoe 72 GMC Super Custom 2500 Custom Camper, my reliable workhorse. Dual gauged tanks, dual battery trays.

12-31-2004, 12:19 PM	#5
784X4GUY Did someone say MUD? Join Date: Aug 2003 Location: Pullman,WA Posts: 1,089	Yeap I have this very same problem, gonna fix it here soon hopefully...Later Mike __________________ Im in the market guys...so keep ya eyes peeled -------------------- Mini trucks are for guys who cant get it up!

12-31-2004, 03:20 PM	#6
greenhorn male Senior Member Join Date: Jan 2003 Location: Bay Area, Northern California Posts: 1,344	Sheeeesh! I just filled the tank with Chevron plus. Now I have to drop the tank to replace the hose. Do you know how heavy these tanks are full. __________________ 03 Tahoe 72 GMC Super Custom 2500 Custom Camper, my reliable workhorse. Dual gauged tanks, dual battery trays.

12-31-2004, 04:03 PM	#7
784X4GUY Did someone say MUD? Join Date: Aug 2003 Location: Pullman,WA Posts: 1,089	Probably pretty damn heavy, Good luck. And don't drop it on yaself lol...Later Mike __________________ Im in the market guys...so keep ya eyes peeled -------------------- Mini trucks are for guys who cant get it up!

12-31-2004, 08:14 AM	#3
smokinn Senior Member Join Date: Aug 2002 Location: omaha,Ne Posts: 617	Check your left tank sending unit could be plugged. Jason

12-31-2004, 09:41 AM	#4
pastorjimk Registered User Join Date: Dec 2004 Location: Perryville, MO Posts: 32	Had the same problem on my 83...The rubber gas lines connecting to the top of the tank had become weak and were crimped. I had to drop the tank and replace the lines. While it's down you might as well clean out the tank

01-01-2005, 04:31 PM	#8
chevymad Registered User Join Date: Jan 2001 Location: skamokawa, WA, USA Posts: 527	You say you have tbi? If so a cracked hose isnt the answer. It would just leak if the hose was cracked because each tank has a fuel pump inside. All lines are under pressure. You most likely have a fuel pump going out in that tank.

01-01-2005, 04:45 PM	#9
Russell Professional Grade Join Date: May 2003 Location: Fort McMurray, Alberta Posts: 7,915	I'd second the weak fuel pump issue... If you need a new used pump, I've got a spare one from a TBI suburban here. I am using the EFI tank to run my TPI, but had to replace the fuel pump with one from a Camaro, so I have a spare TBI pump __________________ 1995 Chevrolet 2 Door Tahoe (6.6L LBZ Duramax / ZF6 / NP241 with 1 ton solid axle swap)

01-01-2005, 05:09 PM	#10
ElGracho Gentleman Jim Driver Join Date: Nov 2002 Location: Poulsbo, WA Posts: 1,553	I have a TBI pump too, it's yours for the price of shipping. I'd also third the bad pump thought... __________________ Joe '75 GMC Gentleman Jim '84 Chev C10 Short Wide - Super duper plain (manual steering, manual brakes, no dome light, no cig lighter) '85 Chev C10 Short Wide - Super plain Vortec 4.8 4L60E trans also: '81 K30, '83 C30 Crew Dually, '84 M1028 CUCV, '85 M1009 CUCV, another '85 C10 SWB, '89 R3500 Flatbed

01-01-2005, 10:43 PM	#11
pastorjimk Registered User Join Date: Dec 2004 Location: Perryville, MO Posts: 32	Just for clarity...I didn't suggest a cracked hose, I said a crimped hose! You all may be right, just sharing my experience with the dual tank/dying engine experience...either way the tank must come down!!!

01-01-2005, 11:11 PM	#12
87 STEPPER STILL PLAYS WITH TRUX Join Date: Nov 2002 Location: Melbourne, Fla. Posts: 2,764	First thing id'e do is connect a high pressure gage 0-100psi and select the tank at fault and then turn the key on and pressurize the system and see if you have at least 35 psi if it's any less the problem could be a bad pump or the x-fer valve isn't making full travle and only opening part way. This is a ruogh figure on the fuel weight useing 6.7 #'s for fuel density @ 60F x's the gallons of the tank about 12 gal. i think and you have the weight= 80.5 Lb's __________________ ~~Bruce~~ MY 87 STEPPER* MY 99 2D/WD TAHOE

01-02-2005, 01:58 AM	#13
greenhorn male Senior Member Join Date: Jan 2003 Location: Bay Area, Northern California Posts: 1,344	Thanks for all the responses, advise and fuel pump offers. I'll try getting that pressure guage and test the pressure once the rain clears a little. I'll let you know if I need a fuel pump. Thanks again! __________________ 03 Tahoe 72 GMC Super Custom 2500 Custom Camper, my reliable workhorse. Dual gauged tanks, dual battery trays.

01-02-2005, 03:13 PM	#14
chevymad Registered User Join Date: Jan 2001 Location: skamokawa, WA, USA Posts: 527	Tbi fuel pressure is only 12-14psi.

01-02-2005, 04:21 PM	#15
greenhorn male Senior Member Join Date: Jan 2003 Location: Bay Area, Northern California Posts: 1,344	I was told 1987 is the first year TBI was introduced to pick-ups and this is the last year of this truck body style. I'd like to buy a repair manual like Chiltons but they might not cover it accurately because it is one of those transition years. I had this problem with a 1973 240z. What brand repair manual would you recommend. __________________ 03 Tahoe 72 GMC Super Custom 2500 Custom Camper, my reliable workhorse. Dual gauged tanks, dual battery trays.



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01-02-2005, 04:41 PM	#16
Blue Beard Registered User Join Date: Jan 2003 Location: Washington State Posts: 8,831	Make sure the switch is good, some of those broke or had wiring issues. Switches are cheap... __________________ 1970 Chev CST 2003 Harley Fatboy 1975 Chevrolet Step Van 1956 Chev Bel Air 1977 Blazer 2WD For Sale $3000.00 1978 Blazer 2WD For Sale $7000.00 1978 Silverado 2005 Monte Carlo

01-02-2005, 05:17 PM	#17
SanitysBane Registered User Join Date: May 2004 Location: Lubbock, Texas Posts: 2,121	get a Helm manual,Click __________________ '96 Nissan Pathfinder '02 Firebird Trans Am. '88 K5 Blazer

01-05-2005, 06:32 PM	#18
1987SierraClassic Registered User Join Date: Sep 2004 Location: Buxton, ME Posts: 91	I agree with everyone else on the fuel pump issue. I had the same problem with a Ford truck. Either the pump is bad or the pickup tube is plugged. Either way you need to drop the tank. I just replaced the tanks in my '87 and found that the easiest way is to remove them by unbolting the brackets from the frame and lowering them straight down. Don't even bother with the straps until the tank is out. The body shop snapped off the strap bolts and I ended up buying new brackets for $50 each. I replaced my 16 gallon tanks with 20 gallon and the only way we could get them back in was to put the brackets on the tank and then lift them into place (even with the bed removed). Luckily mine were near empty. The fuel pump connections are on top of the frame rail just under the cab. Mine came apart really hard and I had the advantage of no bed at the time. I don't know if you can reach them without taking the bed off. I ended up having to cut the rubber lines and replace them. If you get new lines, make sure they are rated for fuel injection...some fuel line isn't. Just thought I'd share my experience! I have the factory manuals for '87 and they don't event mention TBI systems. The Chilton's book mentions it in passing. I found some good information on Chevy fuel injection in a book by Ben Watson "How to Repair and Modify Chevrolet Fuel Injection" ISBN 0-87938-502-2 The book gets into some good detail on how the systems work which is a huge help in diagnosing problems.

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