When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I have a 89 silverado 2wd with 350 tbi. It had 410,000 miles on it and tranny. Have no idea what kind of cam or tbi is and really I have no idea how the top half of a 350 works. So long story short 13 years later I warped both heads and 3 cylinders. For 13 years I replaced EVRYTHING on truck except tranny, motor, intake, and tbi/cam. I bought another 350 with heads. No intake or tbi. Put it in started it up and ran amazing. The motor actually sat in a hay barn for 2 years. That's all I know about it right now (stupid me) anyway I drove it for 2 days no problems then one day it really ran crappy. Little bit of blue smoke. Temp kept bouncing from 180 to 230 so I checked oil and it was little low. 1/2 quart. Checked radiator. Needed half gallon. Filled it up go to start it (it's still around 140 degrees) and it wouldn't start. I know why from my experience and what I heard. It was out of time. I ignition timed it with a light and FINALLY found that sweet spot. Drove it for a week ran awesome!! Yesterday I left for work. Got on the Hwy and above 50mph temp guage went to 240 just a few min. I drove home with it bouncing from 210 to 140. Got below 50mph and it ran solid at 170. (Normal temp is 190) everyone I talk to says if it ran hot on Hwy goin 75 it is either the timing or tbi. I know how to time my truck even without a light. But it is really acting like it isn't timed right at all. I've went high on ignition timing and it actually ran decent but idled high and burned real rich fuel smell. Still no hot start. Anybody with any ideas,or diagnostics? I would like to get a new tbi but have no idea what to look for. I forgot to say the electronic choke has always been a little weird as I was told by a great mechanic but never looked into it.
Last edited by EPON; 03-19-2017 at 08:11 AM.
Reason: New title
Did you use the new or the old water pump? The reason I ask is that serpentine setups use a reverse rotation pump. While V-belt setups use a standard water pump. Mix them up and the engine doesn't get cooled properly.
As for an electronic choke, there isn't one. The ECM adds additional fuel when the engine is cold cranked and started.
I put a new pump in. But I took the stat out for right now so no overheating. The problem I have come up with is that When I turn the cap a little bit to where it idles at 1200 it drives very good. It does idle high but it doesn't bog down like it's not getting enough fuel. it won't hot start When it's like this and blue smoke comes out exaust only When I press the gas. I don't thinks blue smoke is from bad rings or valves cuz it doesn't smoke alot and it does it when i just take off from 1st. Does that mean too much fire for fuel? When I turn the cap to when it idles at 900 (Normal for this truck) it idles and doesn't miss and sounds really good. No blue smoke and it starts hot. But when I put it in 1st and take off it takes alot of gas to keep it from dying. Runs and drives rough. At a stop sign it wants to die but then 10 seconds later it will run at idle so good. B4, I was able to put it in first and release clutch without gas. Now that doesn't happen. It wants to bog down hard and die between all 5 gears. Idk what the heck is going on simply because I think it's electronic in the tbi. I have no idea what else it could be and I've put tons of these motors together. But none with tbi. I just learned about the whole turning cap thing. Don't really understand what it does and why though. Every accessory has been replaced under the hood (except stock tbi/cam) from the clutch reservoir to a whole a.c. unit interchange. Put brand new clutch flywheel and starter when I swapped motors. The tranny,and tbi/cam is only thing stock with 410,000 miles. This is the only other motor that has been it in as well. Hope this all makes sense. I'm desperate to figure it out. This truck is my baby. I won't go to carb but I don't wanna keep This junk tbi that I know nothing about. Its always had high idle after cold start. Sometimes it seems it didn't choke and it just started and ran at 900 rpms. 13 years it has always had a slight miss every few minutes. Sometimes when I drive awhile and come to a stop it seemed like it would choke out and rpms would jump to 1200 to 1500 rpms. Even shifting between gears it would run 1200 and once the clutch is out it would kinda slip down to 1000 and go. I ignored it this whole time cuz didn't know how to fix it as did nobody else. The ecm has been changed twice and it solved this high idle issue for so long both times. But it never permanently fixed it
Its all stock. No performance parts that i know of and im the third owner. My dad was 2nd and he had it for 3 years then gave it to me. He bought it from original owner with 40,000. It definitely needs new gaskets im sure but i don't want to do all that work and money just to end up having to buy something different cuz it doesnt fix it permantly
Problem #1 - you are using a 305 TBI and ECM to run a 350. It will run it,
but it will not be optimized.
Get a thermostat back in there. The correct gasket looks like a square o-ring.
You are not dealing with a 70s era vehicle here.
Troubleshooting is a little different. The ECM relies on many sensor inputs to properly
run your engine. You can't just disable what is not working. It will not run correctly
without being the correct operating temperature.
I have a 95 GMC K1500 truck - 4WD with 305 TBI. Here is a few issues I've had over
the years:
1) the throttle body gaskets will deteriorate in time, and develop vacuum leaks. Use
carb cleaner or a UNLIT propane torch to test for leaks.
2) some distributor rotors arc out to the center mounting post in time, causing spark
loss. Carry a spare rotor.
3) ANY vacuum leaks will raise hell with any computerized FI system. Check those
hard plastic vacuum lines.
4) Throttle Position Sensors (TPS) wear out. Test yours. It is a variable resistor.
5) At some point your intake manifold gaskets will fail. Be sure to use the proper
FelPro gaskets with the small holes at the rear ports.
6) To properly set the timing, in the wiring harness that is by the heater fan inside the
cab, passenger side, there is a connector that you must disconnect to set your base
timing. It could be taped inside the harness. Feel for the bump.
7) Your EGR valve could stick open, or not seal completely, causing rough running.
And you can't just block it off, because the computer will know and you will get a
check engine light.
8) Make sure ALL of your ground connections are good.
9) Replace your fuel filter.
10) You CAN use spray carb cleaner to clean that throttle body. Make sure you
get a nice spray pattern out of both pods, and not dribbles.
Good sir your a true trooper and the only man I've ever talked too and tell me that is off a 305!! Dozens of men told me no it's off a 350 and it would never run with the computer if it was off 305. I've the only one whose said this my whole life simply because I've matched it to identical brand new from AutoZone. But I've never found one even identical to this for a 350 So I was confused on which to look for. Yea I figured the computer is going nuts right now cuz the engine temp is 120 all day. But I have a whole other problem I can't figure out why with 2 brand new 195 stats both of them installed it still gets hot above 50 mph. Like 240 and climbs. Below 50 mph cools down run between 140 to 160. My old motor got hot and I didn't run it hot very long and it warped one head and 2 cylinders. I just bought this motor and put it in. I didn't like it getting hot so I removed that and now it's completely out of ignition time. But I have no idea how to clean throttle body or rebuild it. I have actually strong intentions of buying another tbi since I finally got someone to agree with me. But no idea what to look for. New suggestions. I'm officially done with this tbi
EGR valve. What is that and where? How to test idk. Throttle body sensors is the 2 yellow plugs with 2 wires on top from each? I guess I need to figure this out to get running right. Ain't got the cash to get another tbi probably. The dist, and cap and bug are 5 months old lifetime warranty and actually was installed by a licensed mechanic. Along with plugs and wires. Checked the vacuum lines replaced one with motor swap. 2 new 02 sensors on manifolds. My worry kinda is motor sat in a hay barn for 2 years. Don't know how or if they had it covered or what. Maybe run can of cfoam through oil and change oil again. It's just odd 2 brand new stats surely both wouldn't be bad to cause it to over heat like it did when I first started it with this motor. It drive great till 50mph. Got on Hwy still ran good but water temp kept rising. Got it home hottest it got was 255 and I shut it off. Go to start it back up no hot crank. So I check fluids. Let it cool down a tit go to start it. Acted just like it was out of time ya kno (vrhu..vrhu..) that probably doesn't help but it finally caught and started but idled at 1900. Temp was 140. I sat there and waited 20 min for it to finally idle down and by then it was steady slight miss at 1300rpm. So I took cap loose turnt it not even 1/4 inch clockwise. That brought idle down to a grand and didn't miss a lick. Ran smooth. Go to take off and it pulls it's (I wanna die unless u floor it) ****. So I drove it like that through all 5 gears. It only acted like that from the start 1st gear takeoff to 40mph once I shifted to 4th gear it ran awesome on Hwy. Every once in few min I could here a miss here and there but nothing like it has always done..but getting to 4th gear and 40mph it ran like junk. Went home shut it off. Waited 10 sec and it started right back up and idle at a grand smoothly. Pretty sure the blue smoke I see now isn't oil but it's fuel. I'd say since it sat for 3 months with a full 36 gallon tank it got bad and perhaps why it smells like oil more than fuel. Basically I've driven it 120 miles mostly Hwy. That full tank is now at slight above qrt tank. It got between 300 to 330 miles to full tank b4 swap. I only moved the cap once and it is marked where it was when it ran awesome to 50mph. Then gets hot. I hope this all makes sense and I really appreciate your time and expertise.
Whoops, I misread.....was 350, now 355.
But everything else I said still applies.
Look up what you don't know on YouTube. You will be amazed what you can find on there.
It sounds like you have the wrong water pump. They will both look the same. V belt turns CW, serpentine turns CCW (as standing at the front of the vehicle).
If you have it wrong, the WP will not move the coolant, just beat it like an egg beater. Below 50 mph, there is not much load on the engine,
and it will cool because you have an airflow through the radiator. Above that, with more load, it will get hot. If you were to go up a long,
gradual hill at 30 mph, (little airflow & increased load) you would get hot.
If you need to cool it off quickly, run cold water from the garden hose over the radiator fins.
Today's fuel goes bad quickly. Things might get better when you fill up with fresh fuel.
Throw some dry gas in the tank. Or if you have some, 1 QT of denatured alcohol.
See attached. EGR valve - it is a diaphragm. You can test it with a hand-held vacuum pump. Also, get your fingers behind it with the engine
running and open the valve. Engine should stumble, or even stall. It needs to seal completely when seated. You can TEMPORARILY disable it
by pulling the vacuum line connected to it and inserting a BB in there. Then reattach the vac line.
Took it to a certified mechanic today. His guess was 3 things. Throttle body sensor,egr valve, or may be slightly out of time which he said would be the problem of it not hot cranking but not it getting hot. Now it's his problem if I get it back and it ain't fixed lol thanks for all your help boss. But he says there's no way anyone can tell just by looking at throttle body if it came off a 305 or 350. He said they are identical the only difference is the size of injectors and that would be taking them out and comparing them. Idk either way I'm gonna slap a eldebrock 2 barrel in it. May even buy a 383 stroker rebuild kit and get it bored out with new crank. Dreams my friend. I have a dream!! Thanks again! Be safe
...just by looking at throttle body if it came off a 305 or 350. He said they are identical the only difference is the size of injectors and that would be taking them out and comparing them.
OEM injectors have the part number laser etched into the top of them. Don't even need to remove them from the TBI unit. GM also marked the injectors with two paints dabs on each. If still present that too will tell you which injectors are installed.
Well his diagnostics is the clutch fan. He put 5 new sensors with egr and tbs. He put 3 new vacume lines. He replaced 2 tbi gaskets which means he took it apart. He found the numbers on the bottom side and looked them up. 88 chevy 2wd tbi came stock with slight smaller injectors. They put bigger ones in the 4wd and the late 89s 2 and 4wd. (Mine) he actually took the water pump off made sure it spun and looked good and reinstalled it. Said it was the correct one. Bought another stat(3rd new) and cleaned the block out with it started and running. Filled it full of fluids and still got hot above 50mph and climbed. The other other freaking thing has to be the clutch fan right?? Oh it spins and looks . But what else could make it get hot above 50 and run cold cold (130 to 160) below 50mph. But he already spent 200 in parts and the fan need ordered and it's 150 brand new. Decisions decisions
Make sure the fan blade itself is for the correct rotation.
There were serpentine belt setups with both CW and CCW rotation clutch fans.
This sounds stupid, but what if the fan was blowing the air towards the back of the radiator
and you were traveling at 50 mph, trying to force air through the radiator in the other
direction? Wouldn't that equal no airflow through the core?
Do you have the fan shroud installed?
Did a previous owner put any kind of radiator stop leak in the cooling system
or engine block, plugging it up?
Last edited by NoEmissions84TA; 03-23-2017 at 12:03 AM.
The over heat issue is fixed. It was timed at 10 degrees with a time light so he put it at 6 degrees or so. Solved the over heat issue. Don't know how or why it was an issue with it being out of time. Nothing was put in the motor that's the first question I asked cuz that stuff is terrible for any motor. only problem left is the hot crank issue now. Won't crank at operating temperature. It has a brand new starter ,flywheel, and clutch cuz It was easier to put them in b4 I put the motor in. The 2 anyway. Makes me think it's no doubt electric problem now. But a brand new starter usually isn't bad. Since it's lifetime warranty I'm gonna replace it with another brand new one again and see what happens. Only reason I'd say starter cuz I put a used starter from a 91 silverado and it started with no problems operating temp. All my wires are good and strong. Plz Dont say the cylinoid needs a heat shield cuz thats just silly. The thing about searching youtube for anything on vehicles is it's only folks opinions. All motors are not the same. vehicles may be the same style and year yet their equipped with different electronics and gadgets. Any motor that come stock with a carb is basically the same id say but it all changes after fuel injection. 3 things to make a motor run. Yea we all kno. But that's so not true for any vehicle that's fuel injected. So I never find anything online that I specifically need. Let alone there isnt a video in the world that shows the years 87 to 89 chevy. It's either older or 90s. And everything gm built in the 90s is way different than late 80s. Any early 80s is simple without the sensors and vacuums. It has a whole different style tbi from 90s. Transmission and rear ends are completely different. Wastes my time and upsets me. I want to kno more about this style tbi but can't find any answers. It's obviously a good one it's lasted almost 30 years with 400k+ miles. Can't go wrong with that.
The original GM starter on that vehicle had a heat shield over the solenoid on the starter motor. When I replaced the OEM heavy, old-style starter, I modified the heat shield to fit on the new-style starter.
Yes, they're important.
Original K1500 starter with shield, compared to Delco PG260 mini-starter.
For the record, I advanced the timing on my '88 K1500 to 15 degrees at idle. I had zero problems except the knock sensor was always active, reducing the timing due to detonation. Therefore I put the timing back to stock spec after a few thousand miles. This was with a 205 degree thermostat installed. That thermostat has since been replaced with a 195 degree 'stat.
Have you ever tested the starting/charging power team? It would be worth your while to have the battery load-tested, the alternator voltage and amperage output verified, and the starter draw tested (along with assuring that the wiring harness connecting all these items is sound.)
It has a brand new wire harness installed recently. The battery isnt new But is enough. I believe I'm gonna buy an after market starter. Since this is a better newer motor it probably needs a better starter anyway. I timed my c1500 to just about 6 degrees. Any higher (8) or (10) degrees it wanted to run high ilde and miss several times. That is by far more than enough to crank this motor. It's just the starter is all. Never had one with a heat shield but I ordered one and will install once it arrives with new starter
I also have an 89 k1500. The k1500 had a slight bigger tbi since it is 4x4. The injector ports are bigger than the ones on my c1500 2 wheel 5 speed. My k1500 also has a heat shield on the cylinoid and it is timed at about 8 degrees. Runs like a beast. It is automatic with lock in/out differentials. Both trucks are damn good trucks. I haven't had the k1500 for long as I had my c1500 but I've put motors in both of them now and I'm very impressed. My trucks will last another 15 years for me with new motors. I don't hot rod (like I want) only cuz I can't afford the wear and tear. I'd love to turn my c1500 into a hot rod since it's 2 wheel and so light but I'm not sure what to go with.
Oh indeed they are! K1500 is rusting the cab corners and back fenders. My c1500 is worse cuz it was bondoed b4 I had it. It's rusting rocker panels cab corners. Both bumpers. Back fender. I'll get a pic of my silver c1500. It got the worse but still it's straight body. Badass silver color. But I seen it after it had body work done and it looked so super sexy.
03-19-2017, 07:56 AM
