Tbi swap build thread

[pancake]

when I kink the fuel line by the TBI the gauge goes to over 30psi....do you still think it could be a tank placement problem?

[68 TT]

Originally Posted by pancake

when I kink the fuel line by the TBI the gauge goes to over 30psi....do you still think it could be a tank placement problem?

Something weird is going on and that is the only thing that stands out. You have done everything else to eliminate the variables.

Pick up a Walbro in-line high pressure EFI pump and add it to the system. If things don't get better just sell the pump to somebody on the board and try something else.

Mount it below the fuel tank so it is gravity fed after getting primed.

You won't lose much if any money on the deal and it will help troubleshoot the issue. It may just fix the problem and you won't have to mess with the fuel tank position.

[pancake]

Ok...thanks for the input...I did order a new spring for the fuel regulator...If that does not help I will get the feul pump.

I really cant move the tank to the stock position because I moved the rear axel back 6" and there is no room for it.....it also is safer in the bed...lots of rocks seem to get wedged under the truck

[rfmaster]

Originally Posted by pancake

when I kink the fuel line by the TBI the gauge goes to over 30psi....do you still think it could be a tank placement problem?

Pancake

From your descriptions it appears that fuel pressure readings are slowly dropping over a relatively short period of time. Before hacking anything - place a DVM and measure voltage at fuel pump (at gas tank). Lets make sure that there is no excessive voltage drop anywhere in your wiring (or change in operating voltage). A bad fuel pump relay (worn, pitted contacts) with excessive contact resistance (or a bad wire joint, bad crimp) may be the source of your FP problems. A healthy pump should draw between 2 to 4 amps (depending on the model, back pressure and supply voltage).

By all accounts your present in tank fuel pump should do the trick. However if you are thinking about swapping in tank FP I would go with AC Delco EP-241 (TPI/LT1 rated) should do the trick.

//RF

[mcbassin]

Originally Posted by pancake

Ok...thanks for the input...I did order a new spring for the fuel regulator...If that does not help I will get the feul pump.

I really cant move the tank to the stock position because I moved the rear axel back 6" and there is no room for it.....it also is safer in the bed...lots of rocks seem to get wedged under the truck

I may be wrong...but, I really don't think it is related the spring. You said it was losing pressure during idle. You should be able to hold consistant pressure all the way to WOT with the right pump.

Follow the steps RF and 68 laid out and you will most likely find the problem. these guys are really good...should get paid for their help....my 2 cents.


RFmaster,
I forgot how cool your video is, had to watch it again!

[rfmaster]

Originally Posted by mcbassin

RFmaster,
I forgot how cool your video is, had to watch it again!

Thanks - I am planning to put together a driving video. This will take a bit more work as I would like to show a cold start, street and highway driving around SoCal. It will take a bit of work and editing.

But first we got to get pancake problem solved....

//RF

[pancake]

Fuel pressure update....

I measured voltage at the pump....14 volts when I first start it and the gauge reads 10psi.....5 minutes later when the gauge reads 0psi there is still 14 volts at the pump. There is no voltage drop at the pump, warm or cold.

Took the truck for a short drive, just around the block because there is no plate or lights on it...strictly off road, and it ran fine...no hesation or stumbling.

I am thinking that it may be a bad fuel pressure gauge?

The pressure does climb when I pinch the supply or return line at the TBI.

Will replace the spring when it gets here just because the other one is old and I don't want to waste the srping.

I think I will get another gauge and see if that is the problem...if that does not work I will try a in-line pump added to the system.

[rfmaster]

Pancake

FWIW - Low cost fuel pressure gauges ($12- to $20) are notorious for false readings. It is just a luck of the draw - some are good, and some are just outright junk. I simply got lucky with mine from Summit. The only way to validate this 'theory' is to get a FI test gauge from reputable company (MAC, Snap-On, Actron CP7817 and many others) and test fuel pressure. You can rent FI test gauge from better auto parts stores. Do this check before spending time and money on inline pump.

//RF

[pancake]

Fuel presure issue solved

Cheap Summit fuel gauge was to blame. I went to Auto-Zone and rented/borrowed their gauge and tested my Blazer, right at 12.5 PSI at idle.

I let it run for about 10 minutes and still 12.5 PSI. I will be getting another/better gauge soon.


On a side note....

I have a 83 GMC 1 ton long bed with a fresh 8.1 (bored and stroked 454 to a 496) to tow my blazer to the trails. It has a 16 gallon fuel tank and I have to stop regulary to fill it on long trips. I just pulled a 32 Gallon fuel cell from the Blazer when I did the TBI retrofit. I was thinking about putting the fuel cell in the 83 for long trips but was wondering the best way to transfer the fuel from the fuel cell to the fuel tank. I thought I could use a transfer pump like DirtyLArry showes on the secound page of this thread but I dont want to over fill my 16 gallon tank.

Any ideas?

Thanks again for the help with the TBI....I am sure I will have more questions when I put a TH400 in place of the SM465.

[rfmaster]

Well those cheapo fuel gauges! You are not the first nor the last one to be had by them.

Regarding 16G tank - I am some what surprised since '83 is a long bad and should have had a 20G tank(s) in place. 16G were installed on the 1/2T short beds. The 454 has a good appetite so having auxiliary tank is almost mandatory. I would build a transfer pump setup with overflow return line. This way if 16G is full to capacity excess fuel is returned back to aux tank.

BTW 20G tanks are in this photo:


//RF

[83GMCK2500]

Originally Posted by rfmaster

Regarding 16G tank - I am some what surprised since '83 is a long bad and should have had a 20G tank(s) in place. 16G were installed on the 1/2T short beds.

I've been lurking on this thread for a bit, watching the progress. I just wanted to say that my '83 High Sierra K2500 (originally a 350 truck) has dual 16s in it. We had an '86 C2500 Camper Special w/454 that had dual 20s.

[rfmaster]

The thread has been a bit quiet - so as promised here is the 'drive video'.

Background:
My friend - Carmine has old Mazda 323 (great for part chancing and grocery runs), but the automatic gave out the ghost (I had to tow it back to his house). Rebuilding transmission was deemed too expensive (over $1000), but a good, used $300 trany is a cost effective solution. Long story short found a good trany and this video was captured during our Saturday morning run to JY.

YouTube- JY run in the 75 C20 (aka Beast Drive)

Last 1.5 minutes in this video is on a return leg back home cruising at 65mph taching at 2250 RPM, while WBO (Zeitronix ZT-2) is showing 16.2:1 lean cruise. Can not do that with Carb.

Video editing with Vegas 6.0, Camera - Panasonic PV-GS250.

//RF

[pancake]

Nice video RFmaster

A quick question,

I am having a slight backfire through the exaust...can this be caused by a leaking collector gasket? If not...what should I look at?

It does it a idle and it is slight but it is there.

Thanks.

[rfmaster]

Originally Posted by pancake

Nice video RFmaster

A quick question,

I am having a slight backfire through the exaust...can this be caused by a leaking collector gasket? If not...what should I look at?

It does it a idle and it is slight but it is there.

Thanks.

Hmmmm - can you record audio or video of this backfire? My truck has a 'gurgling' sound when engine is cold (at idle), which IMHO is normal since ECM keeps mixture on the rich side (12.5:1) slowly leaning mixture as engine coolant warms up. Under these conditions there is some un-burned fuel getting into exhaust system causing occasional 'gurgle' like sound. Once engine is warm and in close loop CL no funny sounds other than deep rumble comes out the back. I also get this gurgle like sound under deceleration - with throttle closed and high vacuum engine just sucks all the pooled fuel out of the intake manifold resulting in a very rich mixture - you can see this on WBO display!

In your instance it could be due to a combination of a rich mixture and exhaust leak - I am speculating here. Exhaust leaks have that ticking sound (sounds like a lifter) which corresponds to a leaking cylinder on a exhaust cycle. Headers are notoriously prone to leaks (gaskets get shot and bolts back out). Look for carbon traces - this indicates a spot where exhaust gases escape. Header to head flange, collector to main pipe are two locations I would closely examine for leaks, gaskets, etc.

//RF

[mcbassin]

Originally Posted by rfmaster

The thread has been a bit quiet - so as promised here is the 'drive video'.

Last 1.5 minutes in this video is on a return leg back home cruising at 65mph taching at 2250 RPM, while WBO (Zeitronix ZT-2) is showing 16.2:1 lean cruise. Can not do that with Carb.

//RF

AWESOME VId and truck! RF, Your truck looks much better than the tiny avatar shows! Hey man couple of questions, Where did you score the sweet cluster? Is it from a Burb or blazer? what vintage? How much was the Zeitronics device? What funtions will it perform? thanks,

[rfmaster]

Originally Posted by mcbassin

AWESOME VId and truck! RF, Your truck looks much better than the tiny avatar shows! Hey man couple of questions, Where did you score the sweet cluster? Is it from a Burb or blazer? what vintage? How much was the Zeitronics device? What funtions will it perform? thanks,

Hey Mike - You guys did well with your conversion. Now, only if I can convince my lady that I need a new hmm-hmmm toy!

The story behind my Tach cluster is rather long. Couple years ago I was monitoring e-vil bay for tach equipped clusters for my truck. At one time I even considered doing camaro tach install into a non tach cluster, but after getting all the pieces and mocking them up for a trial fit I was not happy with end results.
From what I can tell most tach equipped clusters that come up for sale are for later 76+ trucks. What annoys me even more is that too many unscrupulous sellers state that cluster will fit 73-86 trucks! Yes, physically they may drop in, but electrically get ready for a fire show! In one auction I was able to determine that this cluster had an ammeter, which is rare since 75 tach equipped cluster is unique. The bid went my way - I practice snipping on e-vil bay. When I got cluster it was wreck - flex circuit was busted in several places and traces were burned. One of the plastic mounting tabs was busted and several others were cracked! Needless to say I was not too happy, but the tach was in good shape (and fully functional). To boot, the lens was yellow like corn. In the end I spent boat load of money to get this cluster into shape. Speedometer was serviced and calibrated by a local spedo shop, I ordered new flex circuit (75 only), new lens and rebuild broken mounting tabs. Instead of 161 bulbs I installed LED's, but they have turned out to be disappointingly dim and I am thinking about change over to brighter ones.

Installation was completed during XMAS of 08.



Left mounting tab was broken and I had to improvise by replaced it with a 90 deg aluminum tab. At the same time a rebuilt tilt steering column...



... and a dash pad along with few other minor items were installed.




Since I always want to know how and what my engine is doing Zeitronix ZT-2 was acquired couple years ago. Let me start by saying that it is not cheap, but it is worth it in the long run especially if you are trying to alter ECM programing to accommodate performance engine requirements, alter fueling tables, change timing, disable unwanted functions, etc. ZT-2 (in conjunction with a laptop) can also act as a data logging system by capturing engine parameters, for example, engine RPM, MAP, TPS, EGT along with AFR and dumping it all into a data file for further analysis. It gets very interesting when you see how engine performs under various operating conditions. For info visit their website:

http://www.zeitronix.com/

//RF

[mcbassin]

RF,
Thanks for the explaination on the cluster and pics. That is exactly what I'm afraid of buying one from ebay. I still don't know if I can make it work but am thinking of trying anyway. Right now I don't even care about the tach as much as a speedo. 91 burb and jimmy clusters (some of them) have electronic speedos. I hope to make one of them work.

[rfmaster]

Originally Posted by mcbassin

RF,
Thanks for the explaination on the cluster and pics. That is exactly what I'm afraid of buying one from ebay. I still don't know if I can make it work but am thinking of trying anyway. Right now I don't even care about the tach as much as a speedo. 91 burb and jimmy clusters (some of them) have electronic speedos. I hope to make one of them work.

Mike
For 90's cluster swap info I would check out FSC. IRC there were couple of threads that dealt with swapping later fully electronic clusters into early 90's burbans. I just do not recall right of hand. It all depends which cluster you want to end up in the end. I just could not stand any longer looking at that huge fuel gauge needle swinging in front of me. Even if you get a busted tach cluster fixing it is not that bad. Electronic spedo should be considered since VSS is built into it solving that pesky problem.

//RF

[68 TT]

Originally Posted by rfmaster

Mike
For 90's cluster swap info I would check out FSC. IRC there were couple of threads that dealt with swapping later fully electronic clusters into early 90's burbans. I just do not recall right of hand. It all depends which cluster you want to end up in the end. I just could not stand any longer looking at that huge fuel gauge needle swinging in front of me. Even if you get a busted tach cluster fixing it is not that bad. Electronic spedo should be considered since VSS is built into it solving that pesky problem.

//RF

The guys on thirdgen.org have figured out what breaks on the tachs and how to fix them as well as getting them calibrated better (more accurate readings) and also to make a six cylinder tach read right for a V-8.

[pancake]

Hello again, been awhile.

Finally got the blazer running well. Took it out four wheeling for a "test drive" and did ok there, but coming back it had issues.

I adjusted the fuel pressure to ~12.5 psi and made sure everything was tight.
It had two codes when I got back 44 and 24. 24 is the VSS. I do not have a neutral safety switch hooked so I think that is why I got that code.

44 is lean 02 sensor....I tightened up everything and seems to work fine.

Only concern I have is to run good the timing is at ~ 12 BTDC. I tried to set it at 0 TDC but it would backfire through the exhaust and run very poor.

Is 12 BTDC to much? Is there something else I should be looking at?

Thanks for the help.

[rfmaster]

Originally Posted by pancake

Hello again, been awhile.

Finally got the blazer running well. Took it out four wheeling for a "test drive" and did ok there, but coming back it had issues.

I adjusted the fuel pressure to ~12.5 psi and made sure everything was tight.
It had two codes when I got back 44 and 24. 24 is the VSS. I do not have a neutral safety switch hooked so I think that is why I got that code.

44 is lean 02 sensor....I tightened up everything and seems to work fine.

Only concern I have is to run good the timing is at ~ 12 BTDC. I tried to set it at 0 TDC but it would backfire through the exhaust and run very poor.

Is 12 BTDC to much? Is there something else I should be looking at?

Thanks for the help.

Hi Pancake

From above it looks like Code 44 was due to exhaust leak which you took care - is that correct???

Timing the TBI system. This is where a lot of people get tripped by ECM controlled ignition system. I am going to assume that you are running 7747 ECM with ASDU calibration. TBI base timing is set with EST connector open! This connector has just one wire (usually tan/white) and hides by the brake booster in OE installation. With connector open the ECM does not control timing - this is when base or initial timing is set. ASDU calibration has initial timing set 0 deg BTDC. The actual and calibration timing values must match! When you open EST set connector idle speed will drop down and engine may have difficulty idling, but since dizzy does not have spring weights idle speed at which you are checking has no effect on initial timing. Once you set base timing shut down engine reconnect EST set connector and clear ECM by disconnecting negative battery terminal. Re start engine and take a look at your idle timing. ASDU calibration has timing tables in the idle RPM/MAP range with 20 to 24deg. This is not a final value since other operational factors may alter the final timing value being sent to dizzy. Usually, I see idle timing bouncing between 18 to 22 degrees in a fully warmed engine.

//RF

[pancake]

Yes I belive I fixed the exhaust leak.

For the timing...I unplug the connector, set the timing at O tdc and turn engine off. Re-connect the connector, disconect the battery, wait 30 sec. and re-connect the battery. This is how I set base timming?

After I do this the truck runs like crap- backfires and has no power...it is un-drivable.

My question is......After setting base timing should I adjust the timming so the truck runs right or should the computer do that?

Thanks for the help.

[rfmaster]

Originally Posted by pancake

Yes I belive I fixed the exhaust leak.

For the timing...I unplug the connector, set the timing at O tdc and turn engine off. Re-connect the connector, disconect the battery, wait 30 sec. and re-connect the battery. This is how I set base timming?

After I do this the truck runs like crap- backfires and has no power...it is un-drivable.

My question is......After setting base timing should I adjust the timming so the truck runs right or should the computer do that?

Thanks for the help.

OK yes that's the correct procedure for setting timing. You do not need to re-adjust after wards (unless your SA tables have been altered from stock). I am going to ask obvious question - is your 0 degree TDC mark on harmonic balancer correct? All too often old, high millage OE balancer have outer ring slip resulting in incorrect timing (and engine vibration). New aftermarket balancers may have timing mark in non stock location - so you have to find and verify TDC.

Just in case remind me your engine details - stock, aftermarket cam - specs, balancer details.

Also which ECM and calibration you are using?

Stock timing tab uses 2 deg steps and big notch is 0 deg:
______________
/
\ 8 deg BTDC
/
\
/ 6 deg BTDC
\
\
/ 0 deg TDC
/
\
/
\______________

//RF

[68 TT]

I would start by verifying TCD of the crank is at TDC on the timing tab / balancer with a positive piston stop like you would do to degree a cam.

This will let you know the parts match and that the outer ring has not slipped and is out of orientation.

It wouldn't be the first time a timing cover and balancer were mismatched to the vintage of crank on a small block.

I have come across this several times. Old block & crank with newer timing cover or balancer.

One the TDC mark is at 12 o'clock and the other it is at about 2 o'clock. Don't ask me why they changed designs.

My Malibu was this way when I got it. 1969 short block with 1979 balancer or timing cover. Timing was about 30 degrees off and it wouldn't run at all when timed "right" by the timing marks.

[pancake]

The engine is a 350ci with a TH400 behind it. It has headers with a 4 wire 02 sensor, TBI abapter plate with no EGR.

7747 ECM with ASDU calibration

Cam shaft is Summit® Camshafts
Camshaft, Hydraulic Flat Tappet, Advertised Duration 252/ 262, Lift .398/ .420, Chevy, Small Block

as for the balancer...it is stock and and so is the timing cover. I will have to see if the outer ring has slipped ...but I don't think so because when I was setting the dizzy I had it at TDC on #1 (with valve cover off and spark plug removed) and the balancer verified that.

I will recheck it.

I did not alter the SA tables and I dont think the previous owner did ( it was stock)